Recent findings suggest that macrophage-tropic human immunodeficiency virus type 1 (HIV-1) produced in colostrum/early breast milk may hold a clue to determine the mechanisms of transmission of HIV-1 via breast-feeding. Here, we show that the majority of CD4+ cells in the colostrum are CD14+ macrophages expressing both chemokine receptors and DC-SIGN, a dendritic cell-specific receptor for HIV-1. The R5-type macrophage-tropic HIV-1 isolate NL(AD8) infected such breast-milk macrophages and caused them to secrete virus particles efficiently; however, the secreted virions showed only a weak transmissibility to their susceptible target, MAGIC-5 cells. When stimulated with interleukin-4, the breast-milk macrophages demonstrated a striking enhancement of expression of DC-SIGN and showed a strong capacity to transmit NL(AD8) virions to MAGIC-5 cells, which was specifically blocked by anti-DC-SIGN-specific antibody. These results suggest that HIV-1 virions captured by DC-SIGN, but not secreted cell-free virions, may be more efficiently transmitted to other compartments, such as the gastrointestinal tract, through acidic gastric juice.

Objective: Measles virus (MV) first infects the human respiratory tract, but the initial target cells are unknown. We examined whether MV infects Langerhans cell-like dendritic cells (LCs) generated from CD14+ monocytes in the presence of GM-CSF, IL-4, and TGF-β1. Methods: Cultured LCs were established as described recently [Biochem Biophys Res Commun 2003;306:674–679]. The expression of immunological markers was detected by FACScan. Infection with MV was assessed by syncytia formation, viral-specific fluorescence, and Western blotting. Results: MV did not infect and replicate the freshly established, unstimulated LCs expressing CD1a, E-cadherin and Langerin but not CD83. Also, CD150, a receptor for MV was not expressed on the surface of the LCs. However, LCs stimulated by mechanical stress such as washing and centrifugation became susceptible to MV infection. Conclusion: A subset of mechanically stimulated LCs but not unstimulated immature ones became susceptible to MV. The actual role of Langerhans cells in local immunity seems to be to suppress unfavorable reactions initiated by virus intrusion.

The effects of Nef molecules on immature dendritic cells (iDCs) were analyzed using recombinant human immunodeficiency virus type 1 (HIV-1) with intact nef gene, pseudotyped with vesicular stomatitis virus glycoprotein, HIV/VSV-G/+Nef. When iDCs were infected with HIV/VSV-G/+Nef, the surface expression of CD1a, a molecule for presenting glycolipid/lipid antigens, was selectively down-regulated among CD1 molecules (CD1a, -b, -c, and -d) as well as class I MHC. Moreover, the CD1a molecules were also down-modulated and co-localized with DsRed2-tagged-Nef in CD1a-transfected cells. Their co-localization was dependent upon CD1a cytoplasmic tail and the CD1a was redistributed from cell surface to LAMP-1+ late endosomal/lysosomal compartment. These findings reveal that the HIV-1-Nef interferes with the intracellular trafficking of CD1a, and suggest the involvement of CD1a-restricted immune effectors in the protective immunity against HIV-1 infection, which implicates the feasibility of virus-derived glycolipid/lipid antigens together with epitope peptides for the vaccine development.

The T-cell subset expressing Vδ2 paired primarily with Vγ2 comprises a majority of γδ T-cells in human adult peripheral blood and expands significantly during a variety of infectious diseases. In contrast, the other subset of γδ T-cells that express Vδ1 is rare among circulating T-cells and its function is poorly understood. Here, we show that a Vγ1Vδ1+ T-cell line, 3-D, established from human peripheral blood by immortalization with Herpesvirus saimiri was able to specifically recognize tumor cells, such as K562 cells, and release cytotoxic granules containing perforin for target cell killing. Some tumor cells, including Daudi cells that are known to be susceptible to killing by Vδ2+ T-cells, were resistant to 3-D killing, implicating distinct pathways for tumor cell control by Vδ1+ and Vδ2+ T-cells. The 3-D T-cell receptor (TCR):CD3 complex reconstituted in TCR-deficient Jurkat cells was capable of transmitting signals, evidenced by activation of the interleukin 2 (IL-2) gene following ligation with anti-CD3 antibody, yet the TCR-reconstituted cells failed to produce IL-2 in response to the target cells. Thus, these results raise the possibility that some Vγ1Vδ1+ T-cells could potentially be stimulated and lyse tumor cells via ligation of TCR/CD3-unassociated molecules.

MHC class I-restricted CD8+ T cells are a crucial component of the host defense against mycobacterial infection in mice, but it has often proved very difficult to identify the CD8 T cell response in humans. Human group 1 CD1 molecules (CD1a, -b, -c) mediate MHC-independent presentation of mycobacteria-derived lipid and glycolipid Ags to CD8+ T cells, and their intracellular localization to the endocytic system may favor efficient monitoring of phagosome-resident mycobacteria. Here, we show that bacillus Calmette-Guérin (BCG)-immunized subjects contain a significant circulating pool of CD8+ T cells that recognize BCG-infected DCs in a CD1-dependent, but MHC-independent, manner. These CD1-restricted T cells efficiently detected live, rather than dead, BCG and produced IFN-γ, an important cytokine for protection against mycobacterial infection. These results emphasize that lipid-reactive CD8+ T cells may contribute to host defense against mycobacterial infection.

For determining the actual antigenic molecules in human immunodeficiency virus type-1 (HIV-1) recognized by cytotoxic T lymphocytes (CTLs) generated among long term non-progressors (LTNP) who might gain protective immunity against HIV-1 through nef-deleted mutants, we have designed replication-defective recombinant HIV-1 particles pseudotyped with vesicular stomatitis virus glycoprotein (VSV-G), carrying an enhanced green fluorescent protein (EGFP) gene in place of the env. VSV-G pseudotyped virions had significantly augmented infectivity for both dividing and non-dividing cells, and EGFP enables single cell analysis to identify the infected cells producing viral antigen p24. These pseudotyped viral particles could also infect Herpesvirus saimiri-transformed human CD4(+) T cells (HVS-T) to produce p24 antigen with or without the nef gene. Although the surface expression of CD4 and class I MHC molecules but not class II MHC, Fas and B7-2 molecules was down-modulated in T cells infected with pseudotyped virions expressing the nef gene, none of the above molecules were down-modulated in the cells infected with nef-deleted pseudotyped virions. VSV-G pseudotyped HIV-1 particles encoding the EGFP gene and HSV-T cells will be useful for analyzing the actual target molecules recognized by CTLs having protective capacity against HIV-1 in vivo and thus, will open new paths for vaccine development.

In the skin, there are unique dendritic cells called Langerhans cells, however, it remains unclear why this particular type of dendritic cell resides in the epidermis. Langerhans cell-like dendritic cells (LCs) can be generated from CD14(+) monocytes in the presence of GM-CSF, IL-4, and TGF-beta1. We compared LCs with monocyte-derived dendritic cells (DCs) generated from CD14(+) monocytes in the presence of GM-CSF and IL-4 and examined the effect of exposure to two distinct bacterial stimuli via Toll-like receptors (TLRs), such as peptidoglycan (PGN) and lipopolysaccharide (LPS) on LCs and DCs. Although stimulation with both ligands induced a marked up-regulation of CD83 expression on DCs, PGN but not LPS elicited up-regulation of expression CD83 on LCs. Consistent with these results, TLR2 and TLR4 were expressed on DCs, whereas only TLR2 was weakly detected on LCs. These findings suggest the actual feature of epidermal Langerhans cells with low-responsiveness to skin commensals.

MHC class I-restricted CD8(+) T cells are a crucial component of the host defense against mycobacterial infection in mice, but it has often proved very difficult to identify the CD8 T cell response in humans. Human group 1 CD1 molecules (CD1a, -b, -c) mediate MHC-independent presentation of mycobacteria-derived lipid and glycolipid Ags to CD8(+) T cells, and their intracellular localization to the endocytic system may favor efficient monitoring of phagosome-resident mycobacteria. Here, we show that bacillus Calmette-Guérin (BCG)-immunized subjects contain a significant circulating pool of CD8(+) T cells that recognize BCG-infected DCs in a CD1-dependent, but MHC-independent, manner. These CD1-restricted T cells efficiently detected live, rather than dead, BCG and produced IFN-gamma, an important cytokine for protection against mycobacterial infection. These results emphasize that lipid-reactive CD8(+) T cells may contribute to host defense against mycobacterial infection.

The authors studied the effects of immunosuppressive peptide cyclosporin A (CsA) on cell fusion efficiency in cells persistently infected with measles virus (448-PI-Vero cells). Treatment of 448-PI-Vero cells with 5 microM CsA enhanced the infusion. In addition, the expression of measles virus antigen on cell surface was increased by treatment with CsA. The addition of phenothiazine, an anti-calmodulin drug, enhanced the fusion of 448-PI-Vero cells in the presence of CsA, although treatment with phenothiazine alone did not affect polykaryocyte formation. The enhancement of fusion efficiency in 448-PI-Vero cells by CsA was suppressed by oligopeptide Z-D-Phe-Phe-Gly, a synthetic oligopeptide that inhibits fusion induced by measles virus. Since the cell content of major virus-specific polypeptides, such as hemagglutinin, nucleoprotein or matrix protein is the same as in untreated controls, this fusion enhancement may be related to transport and accumulation of measles virus glycoproteins.

We have developed a highly specific gene transfer method for adenocarcinoma using a monoclonal antibody against tumor-specific antigen coupled with a plasmid containing the carcinoembryonic antigen (CEA)-specific promoter. The chimeric CEA promoter (CC promoter), which contained an enhancer from the immediate early gene of cytomegalovirus and the CEA promoter, achieved 4- to 5-fold higher transgene expression in CEA-producing cells than the original CEA promoter while maintaining CEA specificity. Furthermore, a complex of a monoclonal antibody against Lewis Y antigen (LYA), the CC promoter-containing plasmid and cationic liposomes (DOTAP) achieved specific gene expression in CEA-producing and LYA-positive adenocarcinoma cell lines that was 200-fold more efficient than in CEA-non-producing and LYA-negative cell lines during a short in vitro incubation. This strategy may be applicable for clinical gene therapy.

The efficacy of adoptive immunotherapy (AIT) using regional lymph node (RLN) cells draining cytokine-gene-transduced tumor vaccine in tumor-bearing immunocompromised mice was investigated. Fibrosarcoma cell line (MCA205) was infected with recombinant retrovirus carrying interleukin (IL) 2 cDNA in vitro, irradiated and used as a tumor vaccine. Experimental treatment using this vaccine for syngeneic C57BL/6 mice with established MCA205 lung metastases did not exert any anti-tumor activity. However, even in long-term MCA205-bearing immunocompromised mice, vaccination with IL2-secreting MCA205 induced tumor-reactive lymphocytes in the RLNs, and AIT using these lymphocytes after stimulation with anti-CD3 antibody and IL2 in vitro resulted in potent antitumor activity in mice bearing established MCA205 lung metastases. Parental MCA205 vaccine, however, failed to induce active RLN cells in mice under the same conditions. Furthermore, ATT using IL2-gene-transduced B16 melanoma vaccine primed RLN cells in long-term MCA205-bearing mice exerted therapeutic activity only in mice with B16 lung metastases, not in mice with MCA205 lung metastases. The present study confirmed that IL2-gene-transduced tumor vaccine induced tumor-specific local immunity in an immuno-compromised state corresponding to clinical situations, and AIT using RLN cells primed with this vaccine should be applicable to the treatment of advanced-stage cancer patients.

Collagen-induced arthritis (CIA) is useful animal model for human rheumatoid arthritis. We investigated the inhibitory effects of portal venous (p.v.) injection of type II collagen (CII) in CIA. The arthritis was suppressed by p.v. injection of CII before immunization for CIA induction. The p.v. route was more effective than intravenous or intragastric routes in the induction of tolerance in CIA. The dose of CII necessary for CIA suppression was 10 micrograms/20 g body weight in p.v. injection. Both anti-CII IgG and anti-CII IgG 2 a levels in serum were reduced in mice injected CII before induction of CIA. However, anti-CII IgG 1 levels did not differ between mice injected with CII and mice injected with buffer alone. Thus, the specific reduction in anti-CII IgG 2 a levels in mice treated by p.v. injection before immunization suggests that the suppression of CIA could be responsible for hypofunction of Th 1 cells. Reduction of anti-CII IgG and suppression of arthritis were observed when CII was injected through portal vein after immunization for CIA as well.

Previously we reported that most antibody secreting cells secreted IgA in the liver, Here we assessed the possibility that parenchymal liver cells (PLC) produced factors, transforming growth factor (TGF)-beta and IL-5, which participate in the differentiation of B cells to IgA-secreting cells. We showed that TGF-beta activity was present in the culture supernatant of PLC, and IL-5 activity was in the lysate of PLC. Moreover, it was confirmed that IL-5 protein produced by PLC was mainly localized in the cell membrane by histochemical staining. The findings that both TGF-beta and IL-5 were produced by PLC should provide useful information concerning the fact that IgA-secreting cells were dominant in the liver.

The effects of cyclosporin A (CsA) on the polykaryocyte formation induced by measles virus (MV) in a monkey kidney cell line (BSC-1) were studied. CsA inhibited virus-induced polykaryocyte formation as well as the production of infectious MV. The development of polykaryocyte formation in the presence of the CsA varied with virus strains, while pretreatment of the cells with 5 microM CsA for 24 hr before the virus infection enhanced polykaryocyte formation. These data demonstrated that CsA not only inhibits but also enhances virus-induced polykaryocyte formation depending on the conditions of its use.

We have established a method for separation of chicken bone-marrow cells using Percoll density gradient centrifugation, and have developed a new method for determining chicken M-CSF-like activity employing a liquid culture. Using this method, we determined M-CSF-like activities in egg yolk, chorioallantoic fluid (CAF) and amniotic fluid (AmF), and studied the effects of M-CSF on development of chicken embryos. M-CSF-like activity in egg yolk was at a high level before the incubation of the egg; it began to decrease on the third day of incubation and rapidly decreased on the fourth day, and no significant activity was detected after the tenth day of incubation. M-CSF-like activity in CAF was very low, and it exhibited almost no change during development. No M-CSF-like activity was detected in AmF throughout the experimental period.

The development of infection seems to be influenced by the characteristics of antigen-presenting cells (APC) in the infection site. Thus, we compared the Semliki Forest virus (SFV)-antigen-presenting capacity of spleen cells, B-cell lymphomas, bone marrow-derived mast cells and nonparenchymal liver cells by measuring the production of lymphokines in SFV-specific T-cell hybridomas. Spleen cells were able to provide the signals needed to stimulate the production of IL-2, IL-4, IL-6 and IFN-gamma, while B lymphomas the signals leading to only IL-2 production. When bone marrow-derived mast cells were used as APC, SFV-specific T-cell hybridomas produced IL-2, IL-4 and IL-6 in the presence of soluble anti-CD3 antibody. However, no lymphokine production was detected when the SFV antigen was used instead of the antibody. Nonparenchymal liver cells containing liver endothelial cells and Kupffer cells have an APC function stimulating the production of IL-2 and IL-6. These findings confirmed that the T-cell hybridomas can be selectively stimulated by different APC to produce different lymphokines, and it would influence the development of the immune-mediated inflammatory response.

The role of M-CSF in the process of mammalian development has been drawing attention. Unlike mammalian embryonic development, in which M-CSF is supplied by the maternal body, avian embryonic development begins and proceeds under the influence of a certain amount of M-CSF present in each fertilized egg, and its concentration can be experimentally controlled while observing the embryo's developmental state. Apart from this fact, aves provide us with many other advantages in the study of embryonic development. It is, however, not easy to separate multipotent hematopoietic stem-cell fractions from avian bone marrow. In addition, because a macrophage colony forming assay in soft agar, though it has been widely used, requires a large number of cells and a long culture period, the method of assay is not adequate for the sensitive detection of M-CSF activity in small scale samples. We have established a method for the depletion of nucleated erythrocytes from chicken bone marrow cell suspensions using percoll density gradient centrifugation, and have also developed a new method for determining chicken M-CSF-like activity employing a liquid culture. In this method, a 100 microliters aliquot of fractionated hematopoietic stem cells, 1 x 10(5), was placed in a well of 96-well flat-bottom culture plate, 100 microliters of sample was then added to each well, and the uptake of neutral red was measured after 4 days of culture. These procedures represent a simple and sensitive means of detecting M-CSF-like activity in chicken serum of x60 to x32 dilutions.(ABSTRACT TRUNCATED AT 250 WORDS)