This report describes the synthesis of [11C]2-(1-methyl-4-piperidinyl)-6-(2-phenylpyrazolo[1,5-a]pyridin-3-yl)-3(2H)-pyridazinone ([11C]FR194921), a highly selective, nonxanthine-type adenosine A1 receptor antagonist, used in brain imaging in rats and conscious monkeys as a potential novel PET tracer. [11C]FR194921 was successfully synthesized in 19 min after [11C]CH3I formation. The radiochemical yield was 38±3%; and radioactivity was 4.1±0.4 GBq, calculated from end of synthesis; radiochemical purity was higher than 99%; and the specific radioactivity was 25.0±8.1 GBq μmol−1 (n=5). In a rat experiment, the distribution of [11C]FR194921 was higher in the hippocampus, striatum and cerebellum regions. This accumulation was significantly decreased by approximately 50% by pretreatment with 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), an adenosine A1 receptor antagonist, which indicated specific binding of the radioligand to adenosine A1 receptors. In conscious monkey PET experiments, [11C]FR194921 accumulated in several regions of the brain, especially in the occipital cortex, thalamus and striatum. These results suggest that [11C]FR194921 can be used as an agent for imaging adenosine A1 receptors in vivo by positron emission tomography (PET).

In a case-control study, prophylaxis with cotrimoxazole for toxoplasmic encephalitis (TE) in HIV-infected patients was evaluated. Cotrimoxazole had been given as PCP prophylaxis. 20 patients with TE were identified and 72 matching control cases were found. All patients had IgG-antibodies to Toxoplasma gondii and CD4+ T-cell counts < or = 100/microliter. The use and duration of cotrimoxazole prophylaxis were recorded. It was found that among the patients with TE, none had used cotrimoxazole for > 70% of the observation time, and that the 1-y incidence was 0% in the control group vs. 41% in those patients without sufficient cotrimoxazole use. The conclusion is that cotrimoxazole is effective as primary prophylaxis for TE, even in a dose of 480 mg daily.

The temporal relationship between viral and surrogate markers and clinical status was analyzed prospectively every 8 weeks in 34 asymptomatic HIV-1-infected persons. After 3 years, 25 persons remained clinically healthy whereas 9 persons showed clinical progression. In accordance with other reports we found that at study entry HIV-RNA load was predictive of clinical progression. All markers tested evolved significantly in time in both progressors and nonprogressors. The HIV RNA load in plasma and HIV DNA load in T cells were linearly related only in nonprogressors. In addition, the RNA/DNA ratio during follow-up was significantly higher in progressors, indicating a higher replication rate in progressors. The HIV DNA load correlated inversely with CD4+ T cell counts and positively with p24 antigenemia in both nonprogressors and progressors. A significant correlation of HIV DNA load with SI phenotype occurred in progressors only. HIV RNA levels correlated with beta 2-microglobulin level and with p24 antigenemia but not with SI phenotype. These three markers can all routinely be measured in plasma; however, only the HIV RNA levels appear to be informative for clinical progression. Six to 8 months before clinical progression, an SI phenotype switch, increased HIV RNA in plasma, and decreased CD4+ T cell counts were all indicative of an impending clinical event.

The current confusion regarding the relevance of endogenous ceramide in mediating GD95/Fas-induced apoptosis is based mainly on (i) discrepancies in kinetics of the ceramide response between different studies using the same apoptotic stimulus and (ii) the observation that late ceramide formation (hours) often parallels apoptosis onset, We investigated CD95-induced ceramide formation in Jurkat cells, using two methods (radiolabeling/thin layer chromatography and benzoylation/ high performance liquid chromatography), which, unlike the commonly used diglyceride kinase assay, discriminate between ceramide species and de novo formed dihydroceramide. We demonstrate that ceramide accumulates after several hours, reaching a I-fold increase after 8 h, kinetics closely paralleling apoptosis induction, No fast response was observed, not even in the presence of inhibitors of ceramide metabolism. The majority (similar to 70%) of the ceramide response remained unaffected when apoptosis was completely inhibited at the level of caspase-3/CPP32 processing by the inhibitor peptide DEVD-CHO. Exogenous cell-permeable C-2-ceramide induced the proteolytic processing of caspase-3, albeit viith somewhat slower kinetics than with CD95, DEVD-CHO dose-dependently inhibited C-2-ceramide- or exogenous sphingomyelinase-induced apoptosis, The results support the idea that ceramide acts in conjunction with the caspase cascade in CD95-induced apoptosis.

The pre-B cell receptor (BCR) complex, consisting of mu heavy chain, a pseudo-light drain, and the Mb-1/B29 heterodimer, directs the transition to the mature B cell stage, Plasma membrane expression of the pre-BCR is extremely low, despite its presumed signaling function, We have compared assembly and intracellular transport of the pre-BCR complex with that of the BCR complex in mature B cells, Synthesis and assembly rate of pre-BCR and BCR components are comparable, However, the pre-BCR is subject to a highly efficient retention mechanism, which only allows exit of a few percent of the complexes from the endoplasmic reticulum (ER). This small transported pool of pre-BCR complexes is significantly enriched for protein-tyrosine kinase activity, as compared with the ER-localized receptor pool, Accordingly, the Src-related tyrosine kinase Lyn was found in the transported glycoprotein action but not in association with ER-localized glycoproteins. Upon introduction of a conventional light chain into pre-B cells, plasma membrane receptor levels increased, but the efficiency of intracellular transport of the receptor complex was not restored to that in mature B cells. This indicates that the ER retention mechanism is not selective for the pseudo-light chain and may be inherent to pre-B cells, We propose that this retention mechanism contributes to the regulation of pre-BCR-mediated signal transduction.

Regional differences in function, metabolism and morphology between proximal colon, distal colon and rectum may be important in the pathogenesis and biologic behaviour of tumours originating from these segments. Thus, the effect of primary prevention of colorectal cancer may also differ from one large bowel segment to another. Therefore, this review underscores that one should be careful extrapolating results obtained in a short segment of the large bowel to the entire colorectum. Obviously, future studies concerning the pathogenesis and possibilities for prevention of large bowel cancer should certainly examine results by subsite as a routine procedure.

In transgenic mice expressing a mutated T cell receptor (TCR) beta chain lacking the variable domain (DeltaV-TCRbeta) T cell differentiation is arrested at the CD4+ CD8+ thymocyte stage. Here, we report that these transgenic animals develop CD4+, CD8+, IL-2 receptor alpha-positive T cell lymphomas at a very high incidence. Introduction of a normal TCRbeta gene into the DeltaV-TCRbeta transgenic mice drastically reduces the tumor incidence, while crossing the DeltaV-TCRbeta transgene onto a recombinase-deficient RAG-1-/- background does not prevent tumor development. Therefore, the induction of T cell lymphomas is a property of the mutated TCRbeta chain. The DeltaV-TCRbeta chain appears at the cell surface as a disulfide-linked DeltaV-TCRbeta/pTalpha dimer in association with CD3gamma and -episilon, but not with CD3delta. This mutated preTCR/CD3 complex is shown to induce pre-T cell proliferation and differentiation, but does not permit formation of a normally sized CD4+8+ thymic compartment. DeltaV-TCRbeta transgenic mice frequently show an expansion of CD4+8+, IL-2 receptor alpha+ pre-T cells early in life. These cells likely represent the population that is subject to oncogenic transformation.

The B cell antigen receptor (BCR) complex consists of transmembrane (m) Ig, in non-covalent association with a disulphide-linked heterodimer of mb-1 and B29 gene products. The MB-1-B29 heterodimer is required for deposition of the BCR at the plasma membrane, as well as for coupling of the antigen receptor to intracellular signal transduction cascades. We have performed biosynthetic labelling studies using the mature B cell line Ramos to investigate the process of assembly of the BCR components. We conclude that association of the four components, Ig-heavy chain (HC) and -light chain (LC), MB-1 and B29, is required and sufficient to permit exit of the BCR complex out of the endoplasmic reticulum (ER). With the short pulse labelling procedures used, no evidence was found for transient participation of other molecules in complex formation. A 32 kDa glycoprotein was identified, which is serologically related to MB-1, but has a more acidic isoelectric point (pl) and a protein backbone of 21 kDa, as compared with 25 kDa for MB-1. This protein did not appear to participate in BCR complex formation and is most likely degraded prior to reaching the cis-Golgi. The MB-1 component was found to be the rate-limiting step in BCR complex formation, while Ig-HC, -LC and B29 are synthesized in excess. Ig-HC and -LC form disulphide-linked tetrameric complexes within 3 min after biosynthesis, with which B29 and MB-1 components associate independently, followed by disulphide bond formation between these heterodimeric partners. While partial BCR complexes containing B29 and mlg-H2L2 tetramers are rapidly formed and have a half-life of a few hours in the ER, entry of MB-1 into these complexes controls exit out of this compartment.

To investigate whether unrecognized systemic lupus erythematosus (SLE) might occur more frequently among psychiatric patients than expected on clinical examination, sera of 100 patients from a psychiatric hospital were tested for the presence of antibodies against nuclear antigens (ANA) and antibodies against DNA. The occurrence of sera positive for ANA was compared with the test results of serum samples of 859 individuals randomly selected from the general population. Positive tests for ANA were found in 7% of the psychiatric patients and 4% of the individuals selected from the population. Antibodies against dsDNA were not found in sera of the psychiatric patients. After categorizing both groups for age and sex, no difference was found as for the frequency of ANA positive sera between both groups, indicating that on the basis of serology, no evidence exists that SLE might be underestimated among psychiatric patients.

The detection of antigen-specific T cell responsiveness, particularly of resting memory lymphocytes, in cultures of peripheral blood mononuclear cells (PBMC) may be hampered by a less than optimal antigen presentation in vitro. Augmented sensitivity of the test system may be achieved by the addition of reagents with a beneficial effect on lymphocyte and antigen-presenting cell (APC) functions. In this study the effect of several biological response modifiers on antigen-specific T cell proliferation was determined, using nickel sulphate and tetanus toxoid as test antigens. IL-1 alpha (100 U/ml), interferon-gamma (IFN-gamma) (10 U/ml), and indomethacin (2 microM) were found to significantly enhance nickel-induced proliferation in PBMC cultures from nickel-hypersensitive donors (n = 6). Tetanus-induced proliferation (n = 5) was similarly enhanced, both by the above supplements and by the addition of polyethylene glycol (PEG) or a neuraminidase treatment of the PBMC before culture. The addition to PBMC cultures of a combination of IL-1 alpha (30 U/ml), IFN-gamma (10 U/ml), and indomethacin (2 microM) is recommended to specifically enhance antigen-induced lymphoproliferative signals.

Immunological ReviewsVolume 132, Issue 1 p. 49-84 Antigen Receptors on T and B Lymphocytes: Parallels in Organization and Function Jannie Borst, Corresponding Author Jannie Borst Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.Jannie Borst, Division of Cellular Biochemistry, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.Search for more papers by this authorGaby S. Brouns, Gaby S. Brouns Department of Immunology, Erasmus University, Rotterdam, The Netherlands.Search for more papers by this authorEvert de Vries, Evert de Vries Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.Search for more papers by this authorMartie C. M. Verschuren, Martie C. M. Verschuren Department of Immunology, Erasmus University, Rotterdam, The Netherlands.Search for more papers by this authorDavid Y. Mason, David Y. Mason Department of Haematology, John Radcliffe Hospital, Oxford, U.K.Search for more papers by this authorJacques J. M. van Dongen, Jacques J. M. van Dongen Department of Immunology, Erasmus University, Rotterdam, The Netherlands.Search for more papers by this author Jannie Borst, Corresponding Author Jannie Borst Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.Jannie Borst, Division of Cellular Biochemistry, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.Search for more papers by this authorGaby S. Brouns, Gaby S. Brouns Department of Immunology, Erasmus University, Rotterdam, The Netherlands.Search for more papers by this authorEvert de Vries, Evert de Vries Division of Immunology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.Search for more papers by this authorMartie C. M. Verschuren, Martie C. M. Verschuren Department of Immunology, Erasmus University, Rotterdam, The Netherlands.Search for more papers by this authorDavid Y. Mason, David Y. Mason Department of Haematology, John Radcliffe Hospital, Oxford, U.K.Search for more papers by this authorJacques J. M. van Dongen, Jacques J. M. van Dongen Department of Immunology, Erasmus University, Rotterdam, The Netherlands.Search for more papers by this author First published: April 1993 https://doi.org/10.1111/j.1600-065X.1993.tb00837.xCitations: 39AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat REFERENCES Abraham, N., Miceli, M. C., Parnes, J. R. & Veilette, A. (1991) Enhancement of T-cell responsiveness by the lymphocyte-specific tyrosine protein kinase p56lck. Nature 350, 62. Alarcon, B., Berkhout, B., Breitmeyer, J. & Terhorst, C. (1988) Assembly of the human T cell receptor-CD3 complex takes place in the endoplasmic reticulum and involves intermediary complexes between the CD3-γ,δ,ɛ core and single T cell receptor α or β chains. J. Biol. Chem. 263, 2953. Alarcon, B., Ley, S. C. Sanchez-Madrid, R. Blumberg, R. S., Ju, S. T. Fresno, M. & Terhorst, C. (1991) The CD3-γ and CD2-δ subunits of the T cell antigen receptor can be expressed within distinct functional TCR/CD3 complexes. EMBO J. 10, 903. Alt, F. W. Yancopoulos, G. D., Blackwell, T. K., Wood, C. Thomas, E., Boss, M., Coffman, R., Rosenberg, N., Tonegawa, S. & Baltimore, D. (1984) Ordered rearrangement of immunoglobulin heavy chain variable region segments. EMBO J. 3, 1209. Anderson, P., Caligiuri, M., Ritz, J. & Schlossman, S. E. (1989) CD3-negative natural killer cells express ζ TCR as part of a novel molecular complex. Nature 341, 159. Appleby, M. W., Gross, J. A., Cooke, M. R. Levin, S. D. Qian, X. & Perlmutter, R. M. (1992) Defective T cell receptor signaling in mice lacking the thymic isoform of p59lyn. Cell 70, 751. Bachhawat, A. K. & Pillai, S. (1991) Distinct intracellular fates of membranes and secretory immunoglobulin heavy chains in a pre-B cell line. J. Cell Biol. 115, 619. Baniyash, M., Garcia-Morales, P. Bonifacino, J. S., Samelson, L. E. & Klausner, R. D. (1988a) Disulfide linkage of the ζ and η chains of the T cell receptor. J. Biol. Chem 263, 9874. Baniyash, M., Garcia-Morales, P., Luong, E., Samelson, L. E. & Klausner, R. D. (1988b) The T cell antigen receptor ζ chain is tyrosine phosphorylated upon activation. J. Biol Chem. 263, 18225. Bauer, S. R., Kudo, A. & Melchers, F. (1988) Structure and pre-B lymphocyte restricted expression of the VpreB gene in humans and conservation of its structure in other mammalian species. EMBO J. 7, 111. Beishuizen, A., Hählen, K., Hagemeijer, A., Verhoeven, M.-A., Hooijkaas, H., Adriaansen, H. J., Wolvers-Tettero, I. L. M., Van Wering, E. R. & Van Dongen, J. J. M. (1991) Multiple rearranged immunoglobulin genes in childhood acute lymphoblastic leukemia of precursor B-cell origin. Leukemia 5, 657. Berkhout, B., Alarcon, B. & Terhorst, C. (1988) Transfection of genes encoding the T cell receptor-associated CD3 complex into COS cells results in assembly of the macromolecular structure. J. Biol. Chem. 263, 8528. Biondi, A., Allavena, P. Rossi, V. Bassan, R., Barbui, T. Champagne, E., Mak, T. W. Minden, M. D., Rambaldi, A & Mantovani, A. (1989) T cell receptor δ gene organization and expression in normal and leukemic natural killer cells. J. Immunol. 143, 1009. Blank, U., Ra, C. Miller, L., White, K., Metzger, H. & Kinet, J.-P (1989) Complete structure and expression in transfected ceils of high affinity IgE receptor. Nature 337, 187. Blumberg, R. S., Alarcon, B., Sancho, J., McDermott, F. V. Lopez, P. Breitmeyer, J. & Terhorst, C. (1990) Assembly and function of the T cell antigen receptor. J. Biol Chem. 265, 14036. Bofill, M., Janossy, G., Janossa, M., Burford, G. D., Seymour, G. J., Wernet, P. & Kelemen, E (1985) Human B cell development. II. J. Immunol. 134, 1531. Bole, D. G., Hendershot, L. M. & Kearney, J. F. (1986) Posttranslational association of immunoglobulin heavy chain binding protein with nascent heavy chains in nonsecreting and secreting hydridomas. J. Celt Biol. 102, 1558. Bonifacino, J. S., Chen, C. Lippincott-Schwartz, J., Ashwell, J. D. & Klausner, R. D. (1988) Subunit interactions within the T-cell antigen receptor: clues from the study of partial complexes. Proc. Natl Acad. Sci. U.S.A. 85, 6929. Bonifacino, J. S., Cosson, P. & Klausner, R. D. (1990) Colocalized transmembrane determinants for ER degradation and subunit assembly explain the intracellular fate of TCR chains. Cell 63, 503. Bonifacino, J. S., Cosson, P., Shah, N. & Klausner, R. D. (1991) Role of potentially charged transmembrane residues in targeting proteins for retention and degradation within the endoplasmic reticulum. EMBO J. 10, 2783. Borgulya, P., Kishi, H., Uematsu, Y. & Von Boehmer, H. (1992) Exclusion and inclusion of α and β T cell receptor alleles. Cell 69, 529. Born, W., Yagüe, J., Palmer, E., Kappler, J. & Marrack, P (1985) Rearrangement of T-ceil receptor β-chain genes during T-cell development. Proc. Natl. Acad. Sci USA 82, 2925. Borst, J., Alexander, S., Elder, J. & Terhorst, C. (1983a) The T3 complex on human T lymphocytes involves four structurally distinct glycoproteins. J. Biol. Chem. 258, 5135. Borst, J., Prendiville, M. A. & Terhorst, C. (1983b) The T3 complex on human thymus- derived lymphocytes contains two different subunits of 20 kDa. Eur. J. Immunol 13, 576. Borst, J., Van de Griend, R. J., Van Oostveen, J. W., Ang, S.-L., Melief, C. J., Seidman, J. G. & Bolhuis, R. L. H. (1987) A T-cell receptor γ/CD3 complex found on cloned functional lymphocytes. Nature 325, 683. Breit, T. M., Wolvers-Tettero, I. L. M., Hählen, K., Van Wering, E. R. & Van Dongen, J. J. M. (1991) Extensive junctional diversity of γδ T-cell receptors expressed by T-cell acute lymphoblastic leukemias. Leukemia 5, 1076. Brenner, M. B., McLean, J., Dialynas, D. P., Strominger, J. L., Smith, J. A., Owen, F. L., Seidman, J. G., Ip, S., Rosen, F. & Krangel, M. S. (1986) Identification of a putative second T-cell receptor. Nature 322, 145. Brouns, G. S., de Vries, E., Van Noesel, C. J. M., Mason, D. Y., Van Lier, R. A. W. & Borst, J. (1993) Structure of the μ/ψL chain complex on human pre-B cells is consistent with a function in signal transduction. Eur J. Immunol (in press). Brunswick, M., Samelson, L. E. & Mond, J. J. (1991) Surface immunoglobulin cross-linking activates a tyrosine kinase pathway in B cells that is independent of protein kinase C. Proc. Natl. Acad Sci USA 88, 1311. Burkhardt, A. L., Brunswick, M., Bolen, J. B. & Mond, J. J. (1991) Anti-immunoglobulin stimulation of B lymphocytes activates src-related protein-tyrosine kinases. Proc. Natl. Acad. Sci. USA 88, 7410. Burrows, P., LeJeune, M. & Kearney, J. F. (1979) Evidence that murine pre-B cells synthesize μ heavy chains but no light chains. Nature 280, 838. Bustelo, X. R. & Barbacid, M. (1992) Tyrosine phosphorylation of the vav proto-oncogene product in activated B cells. Science 256, 1196. Bustelo, X. R., Ledbetter, J. A. & Barbacid, M. (1992) Product of vav proto-oncogene defines a new class of tyrosine protein kinase substrates. Nature 356, 68. Campana, D., Janossy, G., Coustan-Smith, E., Amlot, P. L., Tian, W.-T., Ip, S. & Wong, L. (1989) The expression of T cell receptor-associated proteins during T cell ontogeny in man. J. Immunol 142, 57. Campbell, K. S. & Cambier, J. C. (1990) B lymphocyte antigen receptors (mIg) are non- covalently associated with a disulfide linked, inducibly phosphorylated glycoprotein complex. EMBO J. 9, 441. Campbell, K. S., Hager, E. J. & Cambier, J. C. (1991b) α-chains of IgM and IgD antigen receptor complexes are differentially N-glycosylated mb-I-related molecules. J. Immunol 147, 1575. Campbell, K. S., Hager, E. J., Friedrich, R. J. & Cambier, J. C. (1991a) IgM antigen receptor complex contains phosphoprotein products of B29 and mb-I genes. Proc. Natl. Acad. Sci. USA 88, 3982. Campbell, M.-A. & Sefton, B. M. (1990) Protein tyrosine phosphorylation is induced in murine B lymphocytes in response to stimulation with anti-immunoglobulin. EMBO J. 9, 21–25. Campbell, M.-A., & Sefton, B. W. (1992) Association between B-lymphocyte membrane immunoglobulin and multiple members of the src family of protein tyrosine kinases. Mol Cell Biol 12, 2315. Cantley, L. C. Auger, K. R., Carpenter, C. Duckworth, B., Graziani, A., Kapeller, R. & Soltoff, S. (1991) Oncogenes and signal transduction. Cell 64, 281. Cantrell, D., Davies, A. A., Londei, M., Feldman, M. & Crumpton, M. J. (1987) Association of phosphorylation of the T3 antigen with immune activation of T lymphocytes. Nature 325, 540. Cantrell, D. A., Friedrich, B., Davies, A. A., Gullberg, M. & Crumpton, M. J. (1989) Evidence that a kinase distinct from protein kinase C induces CD3 γ-subunit phosphorylation without a concomitant down-regulation in CD3 antigen expression. J. Immunol. 142, 1626. Carter, R. H. & Fearon, D. T. (1992) CDI9: lowering the threshold for antigen receptor stimulation of B lymphocytes. Science 256, 105. Carter, R. H., Park, D. J., Rhee, S. G. & Fearon, D. T. (1991) Tyrosine phosphorylation of phospholipase C induced by membrane immunoglobulin in B lymphocytes. Proc. Natl Acad. Sci. USA 88, 2745. Casillas, A., Hanekom, C. Williams, K., Katz, R. & Nel, A. E. (1991) Stimulation of B- cells via the membrane immunoglobulin receptor or with phorbol myristate 13-acetate induces tyrosine phosphorylation and activation of a 42-kDa microtuble associated protein-2 kinase. J. Biol. Chem. 266, 19088. Chan, A. C. Irving, B. A., Fraser, J. D. & Weiss, A. (1991) The ζ chain is associated with a tyrosine kinase and upon T-cell antigen receptor stimulation associates with ZAP- 70, a 70 kDa tyrosine phosphoprotein. Proc. Natl Acad. Sci. USA 88, 9166. Chan, A. C. Iwashima, M., Turck, C. W. & Weiss, A. (1992) ZAP-70: a 70 kd protein- tyrosine kinase that associates with the TCR C chain. Cell 11, 649. Chen, J., Stall, A. M., Herzenberg, L. A. & Herzenberg, L. A. (1990) Differences in glycoprotein complexes associated with IgM and IgD on normal murine B cells potentially enable transduction of different signals. EMBO J. 9, 2117. Cherayil, B. J. & Pillai, S. (1991) The ω/λ5 surrogate immunoglobulin light chain is expressed on the surface of transitional B lymphocytes in murine bone marrow. J. Exp. Med 173, 111. Chotia, C. Boswell, D. R. & Lesk, A. M. (1988) The outline structure of the T-cell αβ receptor. EMBO J. 1, 3745. Clark, M. R., Campbell, K. S., Kazlauskas, A., Johnson, S. A., Hertz, M., Potter, T. A., Pleiman, C. & Cambier, J. C. (1992) The B cell antigen receptor complex: association of Ig-α and Ig-β with distinct cytoplasmic effectors. Science 258, 123. Coggeshall, K. M., McHugh, J. C. & Altman, A. (1992) Predominant expression and activation-induced tyrosine phosphorylation of phospholipase C-γ2 in B lymphocytes. Proc. Natl. Acad Sci. USA 89, 5660. Cooke, M. P. Abraham, K. M., Forbush, K. A. & Perlmutter, R. M. (1991) Regulation of T cell receptor signalling by a src family protein-tyrosine kinase (p59fyn). Cell 65, 281. Corcos, D., Iglesias, A., Dunda, O., Bucchini, D. & Jami, J. (1992) Allelic exclusion in transgenic mice expressing a heavy chain disease-like human μ protein. Eur. J. Immunol 21, 2711. Davies, A. A., Cantrell, D. A., Hexham, J. M., Parker, P. J., Rothbard, J. & Crumpton, M. J. (1987) The human T3 γ chain is phosphorylated at serine 126 in response to T lymphocyte activation. J. Biol Chem. 262, 10918. Davis, M. M. & Bjorkman, P. (1988) T-cell antigen receptor genes and T-cell recognition. Nature 334, 395. DeFranco, A. L. (1987) Molecular aspects of B-lymphocyte activation. Ann. Rev. Cell Biol 3, 143. De la Hera, A., Müller, U., Olsson, C. Isaaz, S. & Tunnacliffe, A. (1991) Structure of the T cell antigen receptor (TCR): Two CD3ɛ subunits in a functional TCR/CD3 complex. J. Exp. Med 173, 7. Downward, J., Graves, J. D. Warne, P. H., Rayter, S. & Cantrell, D. A. (1990) Stimulation of p21ras upon T-cell activation. Nature 346, 719. Ettehadieh, E., Sanghera, J. S., Pelech, S. L., Hess-Bienz, D., Watts, J., Shastri, N. & Aebersold, R. (1992) Tyrosyl phosphorylation and activation of MAP kinases by p56lck. Science 255, 853. Flaswinkel, H. & Reth, M. (1992) Molecular cloning of the Ig-a subunit of the human B-cell antigen receptor complex. Immunogenetics 36, 266. Gassman, M., Guttinger, M., Amrein, K. E. & Burn, P. (1992) Protein tyrosine kinase p59 ‘*’ is associated with the T cell receptor-CD3 complex in functional human lymphocytes. Eur J. Immunol. 22, 283. Gearhart, P. J. & Bogenhagen, D. E. (1983) Clusters of point mutations are found exclusively around rearranged antibody variable genes. Proc. Natl Acad. Sci. USA 80, 3439. Geisler, C. (1992) Failure to synthesize the CD3 γ chain. J. Immunol 148, 2437. Gold, D. P. Puck, J. M., Pettey, C. L., Cho, M., Coligan, J., Woody, J. N. & Terhorst, C. (1986) Isolation of cDNA clones encoding the 20 K non-glycosylated polypeptide chain of the human T cell receptor/T3 complex. Nature 321, 431. Gold, M. R., Chan, V. W.-F., Turck, C. W. & DeFranco, A. L. (1992) Membrane Ig crosslinking regulates phosphatidylinositol 3-kinase in B lymphocytes. J. Immunol. 148, 2012. Gold, M. R., Law, D. A. & DeFranco, A. L. (1990) Stimulation of protein tyrosine phosphorylation by the B-lymphocyte antigen receptor. Nature 345, 810. Gold, M. R., Matsuuchi, L., Kelly, R. B. & DeFranco, A. L. (1991) Tyrosine phosphorylation of components of the B-cell antigen receptors following receptor crosslinking. Proc. Natl. Acad. Sci. USA 88, 3436. Goodnow, C. C. Crosbie, J., Adelstein, S., Lavoie, T. B., Smith-Gill, S. J., Brink, R. A., Pritchard-Briscoe, H., Wotherspoon, J. S., Loblay, R. H., Raphael, K., Trent, R. J. & Basten, A. (1988) Altered immunoglobulin expression and functional silencing of self-reactive B lymphocytes in transgenic mice. Nature 334, 676. Gu, H., Kitamura, D. & Rajewsky, K. (1991) B cell development regulated by gene rearrangement: arrest of maturation by membrane-bound DP protein and selection of DH element reading frames. Cell 65, 47. Graziadei, L., Riabowol, K. & Bar-Sagi, D. (1990) Co-capping of ras proteins with surface immunoglobulins in B lymphocytes. Nature 347, 396. Groettrup, M., Baron, A., Griffiths, G., Palacios, R. & Von Boehmer, H. (1992) T cell receptor (TCR) β chain homodimers on the surface of immature but not mature α, γ, δ chain deficient T cell lines. EMBO J. 11, 2735. Ha, H., Kubagawa, H. & Burrows, P. D. (1992) Molecular cloning and expression pattern of a human gene homologous to the murine mb-I gene. J. Immunol. 148, 1526. Haas, I. G. & Wabl, M. (1983) Immunoglobulin heavy chain binding protein. Nature 306, 387. Hengartner, H., Odermatt, B., Schneider, R., Schreyer, M., Walle, G., MacDonald, H. R. & Zinkernagel, R. M. (1988) Deletion of self-reactive T cells before entry into the thymus medulla. Nature 336, 388. Hermanson, G. G., Eisenberg, D., Kincade, R. W. & Wall, R. (1988) B29: A member of the immunoglobulin gene superfamily exclusively expressed on B-lineage cells. Proc. Natl. Acad. Sci. USA 85, 6890. Hochstenbach, F., David, V., Watkins, S. & Brenner, M. B. (1992) Endoplasmic reticulum resident protein of 90 kilodaltons associates with the T- and B-cell antigen receptors and major histocompatibility complex antigens during their assembly. Proc. Natl Acad. Sci. USA 89, 4734. Hokland, P., Ritz, J., Schlossman, S. F. & Nadler, L. M. (1985) Orderly expression of B cell antigens during the in vitro differentiation of nonmalignant human pre-B cells. J. Immunol. 135, 1746. Hollis, G. F., Evans, R. J., Stafford-Hollis, J. M., Korsmeyer, S. J. & McKearn, J. P (1989) Immunoglobulin λ light-chain-related genes 14.1 and 16.1 are expressed in pre-B cells and may encode the human immunoglobulin ω light-chain protein. Proc. Natl Acad. Sci. USA 86, 5552. Hombach, J., Leclerq, L., Radbruch, A., Rajewsky, K. & Reth, M. (1988b) A novel 34- kD protein co-isolated with the IgM molecule in surface IgM-expressing cells. EMBO J. 7, 3451. Hombach, J., Lottspeich, F. & Reth, M. (1990a) Identification of the genes encoding the IgM-α and Ig-β components of the IgM antigen receptor complex by aminoterminal sequencing. Eur J. Immunol. 20, 2795. Hombach, J., Sablitzky, F., Rajewsky, K. & Reth, M. (1988a) Transfected plasmacytoma cells do not transport the membrane form of IgM to the cell surface. J. Exp. Med. 167, 652. Hombach, J., Tsubata, T. Leclerq, L., Stappert, H. & Reth, M. (1990b) Molecular components of the B-cell antigen receptor complex of the IgM class. Nature 343, 760. Honjo, T. Shimizu, A. & Yaoita, Y. (1989) Constant-region genes of the immunoglobulin heavy chain and the molecular mechanism of class switching. In: Immunoglobulin genes. Eds. T. Honjo, F. W. Alt & T. H. Rabbitts Academic Press Ltd., London , U.K. , p. 123. Hsi, E. D., Siegel, J. N., Minami, Y. Luong, E. T. Klausner, R. D. & Samelson, L. E. (1989) T cell activation induces rapid tyrosine phosphorylation of a limited number of cellular substrates. J. Biol. Chem. 264, 10836. Hutchcroft, J. E., Harrison, M. L. & Geahlen, R. L. (1991) B lymphocyte activation is accompanied by phosphorylation of a 72-kDa protein-tyrosine kinase. J. Biol. Chem. 266, 14846. Hutchcroft, J. E., Harrison, M. L. & Geahlen, R. L. (1992) Association of the 72-kDa protein-tyrosine kinase PTK72 with the B cell antigen receptor. J. Biol. Chem. 267, 8613. Iglesias, A., Kopf, M., Williams, G. S., Bühler, B. & Kohler, G. (1991) Molecular requirements for the μ-induced light chain gene rearrangement in pre-B cells. EMBO J. 10, 2147. Irving, B. A. & Weiss, A. (1991) The cytoplasmic domain of the T cell receptor C chain is sufficient to couple to receptor-associated signal transduction pathways. Cell 64, 891. Jenkins, M. K. & Schwartz, R. H. (1987) Antigen presentation by chemically modified splenocytes induces antigen-specific T cell unresponsiveness in vitro and in vivo. J. Exp. Med. 165, 302. Jensen, J. P., Hou, D., Ramsburg, M., Taylor, A., Dean, M. & Weissman, A. M. (1992) Organization of the human T cell receptor ζ/η gene and its genetic linkage to the FcγRII-FcγRIII gene cluster. J. Immunol 148, 2563. Jin, Y. J., Clayton, L. K., Howard, F. D., Koyasu, S., Sieh, M. Steinbrich, R., Tarr, G. E. & Reinherz, E. L. (1990) Molecular cloning of the CD37 subunit identifies a CD3C-related product in thymus-derived cells. Proc. Natl Acad. Sci. USA 87, 3319. June, C. H., Fletcher, M. C. Ledbetter, J. A., Schieven, G. L., Siegel, J. N., Phillips, A. F. & Samelson, L. E. (1990) Inhibition of tyrosine phosphorylation prevents T-cell receptor-mediated signal transduction. Proc. Natl Acad. Sci. USA 87, 7722. Justement, L. B., Campbell, K. S., Chien, N. C. & Cambier, J. C. (1991) Regulation of B cell antigen receptor signal transduction and phosphorylation by CD45. Science 252, 1839. Kamps, W. A. & Cooper, M. D. (1982) Microenvironmental studies of pre-B and B cell development in human and mouse fetuses. J. Immunol. 129, 526. Kappler, J. W., Roehm, N. & Marrack, P. (1987) T cell tolerance by clonal elimination in the thymus. Cell 49, 273. Karasuyama, H., Kudo, A. & Melchers, E. (1990) The proteins encoded by the VpreB and λ5 pre-B cell-specific genes can associate with each other and with μ heavy chain. J. Exp. Med 111, 969. Kashiwamura, S.-L, Koyama, T. Matsuo, T. Steinmetz, M., Kimoto, M. & Sakaguchi, N. (1990) Structure of the murine mb-I gene encoding a putative sIgM-associated molecule. J. Immunol. 145, 337. Kerr, W. G., Cooper, M. D., Feng, L., Burrows, P. D. & Hendershot, L. M. (1989) Mu heavy chains can associate with a pseudo-light chain compex (ψ/L) in human pre-B cell lines. Int. Immunol. 1, 355. Kisielow, P. Blüthmann, H., Staerz, U. D., Steinmetz, M. & Von Boehmer, H. (1988) Tolerance in T-cell receptor transgenic mice involves deletion of nonmature CD4+ 8+ thymocytes. Nature 333, 742. Kitamura, D., Kudo, A., Schaal, S., Muller, W. Melchers, F. & Rajewsky, K. (1992) A critical role of λ5 protein in B cell development. Cell 69, 823. Kitamura, D. & Rajewsky, K. (1992) Targeted disruption of μ chain membrane exon causes loss of heavy chain allelic exclusion. Nature 356, 154. Kitamura, D., Roes, J., Kühn, R. & Rajewsky, K. (1991) A B cell-deficient mouse by targeted disruption of the membrane exon of the immunoglobulin μ chain gene. Nature 350, 423. Klausner, R. D., Lippincott-Schwartz, J. & Bonifacino, J. S. (1990) The T cell antigen receptor: insights into organelle biology. Ann. Rev. Cell Biol. 6, 403. Kocks, C. & Rajewsky, K. (1988) Stepwise intraclonal maturation of antibody affinity through somatic hypermutation. Proc. Natl. Acad. Sci. USA 85, 8206. Koning, F. (1991) Lymphocyte antigen receptors: a common design Immunol Today 12, 100. Koning, R. Maloy, W. L. & Coligan, J. E. (1990) The implications of subunit interactions for the structure of the T cell receptor-CD3 complex. Eur. J. Immunol. 20, 299. Koyasu, S., McConkey, D. J., Clayton, L. K., Abraham, S., Yandava, B., Katagiri, T. Moingeon, P., Yamamoto, T. & Reinherz, E. L. (1992) Phosphorylation of multiple CD3C tyrosine residues leads to formation of pp21 in vitro and in vivo. J. Biol. Chem. 267, 3375. Krangel, M. S., Bierer, B. E., Devlin, P., Clabby, M., Strominger, J. L., McLean, J. & Brenner, M. B. (1987) T3 glycoprotein is functional although structurally distinct on human T-cell receptor γ T lymphocytes. Proc. Natl. Acad. Sci. USA 84, 3817. Krimpenfort, P., Ossendorp, F., Borst, J., Melief, C. & Berns, A. (1989) T cell depletion in transgenic mice carrying a mutant gene for TCR-β. Nature 341, 742. Krissansen, G. W., Owen, M. J., Verbi, W. & Crumpton, M. J. (1986) Primary structure of the T3-y subunit of the T3/T cell antigen receptor complex deduced from cDNA sequences: evolution of the T3-γ and δ subunits. EMBO J. 5, 1799. Kudo, A. & Melchers, F. (1987) A second gene, VpreB in the λ5 locus of the mouse, which appears to be selectively expressed in pre-B lymphocytes. EMBO J. 6, 2267. Lane, P. J. L., Ledbetter, J. A., McConnell, F. M., Draves, K., Deans, J., Schieven, G. L. & Clark, E. A. (1991) The role of tyrosine phosphorylation in signal transduction through surface Ig in human B cells. J. Immunol. 146, 715. Lanier, L. L., Yu, G. & Phillips, J. H. (1989) Co-association of CD3C with a receptor (CDI6) for IgG Fc on human natural killer cells. Nature 342, 803. Leprince, C. Draves, K. E., Ledbetter, J. A., Torres, R. M. & Clark, E. A. (1992) Characterization of molecular components associated with surface immunoglobulin M in human B lymphocytes: presence of tyrosine and serine/threonine protein kinases. Eur J. Immunol. 22, 2093. Letoumeur, F. & Klausner, R. D. (1992) Activation of T cells by a tyrosine kinase activation domain in the cytoplasmic tail of CD3 ɛ. Science 255, 79. Ma, A., Fisher, P., Dildrop, R., Oltz, E., Rathbun, G., Achacoso, P., Stall, A. & Alt, E. W. (1992) Surface IgM mediated regulation of RAG gene expression in Eμ-N-myc B cell lines. EMBO J. 11, 2727. Manz, J., Denis, K., Witte, O., Brinster, R. & Storb, U. (1988) Feedback inhibition of immunoglobulin gene rearrangement by membrane μ, but not by secreted μ heavy chain. J. Exp. Med 168, 1363. Margolis, B., Hu, R. Katzav, S., Li, W., Oliver, J. M., Ullrich, A., Weiss, A. & Schlessinger, J. (1992) Tyrosine phosphorylation of vav proto-oncongene product containing SH2 domain and transcription factor motifs. Nature 356, 71. Mason, D. Y., Cordell, J. L., Tse, A. G. D., Van Dongen, J. J. M., Van Noesel, C. J. M., Micklem, K., Pulford, K. A. F., Valensi, F., Comans-Bitter, W. M., Borst, J. & Gatter, K. C. (1991) The IgM-associated protein mb-1 as a marker of normal and neoplastic B cells. J. Immunol 147, 2474. Mason, D. Y., Van Noesel, C. J. M., Cordell, J. L., Comans-Bitter, W. M., Micklem, K., Tse, A. G. D., Van Lier, R. A. W. & Van Dongen, J. J. M. (1992) The B29 and mb-1 polypeptides are differentially expressed during human B cell differentiation. Eur J. Immunol 22, 2753. Meuer, S. C. Acuto, O., Hussey, R. E., Hodgdon, J. C. Fitzgerald, K. A., Schlossman, S. E. & Reinherz, E. L. (1983b) Evidence for the T3-associated 90 K heterodimer as the T cell antigen receptor. Nature 303, 808. Meuer, S. C. Fitzgerald, K. A., Hussey, R. E., Hodgdon, J. C. Schlossman, S. F & Reinherz, E. L. (1983a) Clonotypic structures involved in antigen-specific human T cell function: relationship to the T3 molecular complex. J. Exp. Med. 157, 705. Minami, Y. Weissman, A. M., Samelson, L. E. & Klausner, R. D. (1987) Building a multichain receptor: synthesis, degradation, and assembly of the T-cell antigen receptor.

The biotransformation activity of the mono-oxygenase enzyme, 7-ethoxycoumarin-O-deethylase (EOD), was investigated in the upper digestive tract of colon cancer patients, and compared with patients with and without neoplasia. The three groups studied comprised 23 control, 17 metastasized colon cancer and 16 metastasized breast cancer patients. EOD activity was determined by spectrofluorometry in duodenal biopsies obtained during gastroduodenoscopy. No correlation between the presence of colon or breast cancer and the level of EOD activity was observed. It was concluded that biotransformation enzymes can be easily determined in duodenal biopsies derived during. gastroduodenoscopy. The role of EOD in the biogenesis of colon cancer seems to be limited.

CD27 is a member of the nerve growth factor receptor family, that includes two types of tumor necrosis factor receptor, CD40 and Fas/Apo-1. Human CD27 has been found only on lymphocytes. In T cells, its expression strongly increases in a transient fashion upon antigenic stimulation, suggesting that CD27 plays a role during T cell activation. To analyze the function of CD27, we have identified the murine CD27 at the cDNA and protein level. Murine CD27 shows an identity of 65% compared with human CD27. The amino-terminal cysteine-rich region, i. e. the putative ligand-binding domain, and the carboxy-terminal part of the cytoplasmic domain are approximately 80% identical in man and mouse. Murine CD27 has 29% identity to 4-1BB, another lymphocyte-specific member of the receptor family defined only at the cDNA level. Murine CD27 and 4-1BB have 39% homology in the cysteine-rich domain and share a conserved region in the cytoplasmic tail. Expression studies identified murine CD27 mRNA in thymus and spleen, but not in non-lymphoid tissues, while 4-1BB mRNA was not detected in any tissue tested. In resting T cells, only murine CD27 mRNA was found, while in activated T cells murine CD27 as well as 4-1BB were present at high levels. Murine CD27 and 4-1BB mRNA are expressed with different kinetics during T cell activation, suggesting that these molecules play different roles in this process. Peptide antisera identified murine CD27 as a 45-kDa protein on thymocytes and activated T cells, while 4-1BB was precipitated as a 35-40-kDa protein from activated T cells.

Prior to immunoglobulin (Ig) light (L) chain rearrangement, pre‐B cells can express μ heavy (H) chains at the cell surface in association with pseudo (ψ) L chains. This complex may be essential for B cell development. We have investigated the composition of the μ/ψL chain complex of a human pre‐B cell line, in view of its potential role in transmembrane signal transduction. The μ/λ. receptor of a mature B cell line was analyzed in comparison. The μ/ψL chain complex is associated with disulfide‐linked molecules that are homologous or identical to the mb‐1 and B29 proteins, known to be integral components of membrane Ig receptors on mature B cells. Both receptors contain tyrosine (Tyr) kinase activity. In the μ/λ receptor, the lyn and lck Tyr kinases could clearly be identified. The mb‐1 and B29 proteins in both μ/λ and μ/ψL chain receptors are substrates for in vitro phosphorylation on Tyr, but also on serine (Ser) and threonine (Thr) residues. The undefined μ‐associated Ser/Thr kinase also phosphorylates the sre‐related kinases in the μ/λ, receptor and a 43‐kDa μ‐associated protein that is present in both complexes. The 43‐kDa protein may be an integral part of both receptor types, or a transiently associated molecule instrumental in the signaling process. We conclude that the μ/ψL receptor on human pre‐B cells fulfills the presently known criteria to function as a signal transduction unit.

A TCR-beta gene lacking V domain sequences (delta V-TCR-beta) was inserted into the germline of mice. Expression of the transgene inhibited endogenous TCR-beta, but not TCR-alpha gene rearrangement and expression. The mutated TCR-beta gene affected alpha beta T cell development: the common thymocyte pool was normal in cell number, with cells expressing CD4 and CD8, but the mature, "CD3bright" population expressing either CD4 or CD8 molecules was reduced by 90%. To help understand these effects on TCR-beta gene rearrangement and T cell development, biosynthesis of the delta V-TCR-beta protein was analyzed in a tumor cell line derived from a transgenic mouse. Despite absence of the V domain, the delta V-TCR-beta chain paired with endogenous TCR-alpha chains and assembled with CD3 gamma, -delta, -epsilon, and -zeta components in the endoplasmatic reticulum, followed by transport through the Golgi complex to the plasma membrane. Therefore, assembly of the complex, and even cell surface expression, may be relevant for allelic exclusion of the TCR-beta gene. In the common thymocyte population, the CD3 components, endogenous TCR-alpha, and the delta V-TCR-beta gene product were expressed at the RNA level, but endogenous TCR-beta was not. The TCR-alpha delta beta/CD3 complex was present at the cell surface at low levels and was functional in terms of anti-CD3-induced Ca2+ mobilization. The observed arrest of alpha beta T cell development at the CD4+8+ thymocyte stage indicates that ligand recognition by the TCR, with contribution of the beta-chain V domain, is not required for transition of CD4-8- thymocytes to the CD4+8+ phenotype, but necessary for entry into the "single positive," CD3bright differentiation stage.

CD27 is a transmembrane glycoprotein found exclusively on human T and B lymphocytes. It belongs to a recently identified receptor family, whose members are involved in cell differentiation and survival. This family includes the nerve growth factor receptor, two different types of tumor necrosis factor, receptors the Fas antigen, and the B cell-specific protein CD40. T cell activation via the antigen receptor strongly enhances CD27 membrane expression, suggesting a role for CD27 during T cell differentiation. A soluble form of CD27 (sCD27) is released into the supernatant of activated T cells, and detected in serum and urine of healthy individuals and patients.We have investigated the mechanism underlying the generation of sCD27. One mRNA encodes both the transmembrane receptor and sCD27, as shown by cDNA transfection. In line with this, only one CD27 precursor protein is found, that is processed to the mature receptor by extensive O-linked glycosylation. All newly synthesized protein is rapidly transported to the plasma membrane; no internal pool of mature protein is detectable. The transmembrane form gives rise to sCD27 after arrival at the cell surface, most likely via a proteolytic event, that does not involve receptor internalization.