BACKGROUND:Antibacterial drugs appear to be effective in shortening the illness of a majority of cases of travelers' diarrhea.METHODS:This was a subanalysis from two randomized, double-blind, placebo-controlled trials in adult travelers with acute diarrhea treated with rifaximin 200 mg three times a day or placebo for 3 days. Efficacy was assessed by the interval beginning with the first dose of medication and ending with the last unformed stool passed after becoming well [time to last unformed stool (TLUS)]; number of unformed stools passed; percent with clinical improvement; and incidence of wellness achieved.RESULTS:Stool pathogens were not identified in pretreatment samples in 122 of 322 (38%) patients and 106 of 230 (46%) randomized to rifaximin and placebo, respectively. Among pathogen-negative patients, rifaximin was more effective than placebo for median TLUS (33 vs 68 h, p < 0.005), mean number of unformed stools passed (6.5 vs 8.6, p < 0.0001), and clinical wellness (77% vs 61%, p = 0.01). The adverse-event profiles between rifaximin and placebo were similar.CONCLUSIONS:More than one third of patients with travelers' diarrhea had pathogen-negative illness. Rifaximin was effective in treating the illness without associated side effects. These results are consistent with the hypothesis that undetected bacterial pathogens are the most likely cause of travelers' diarrhea without definable cause.

ABSTRACT Rifaximin is an oral antibiotic indicated for treatment of traveler's diarrhea. Rifaximin pharmacokinetics were evaluated in individuals challenged with Shigella flexneri. Peak plasma rifaximin concentrations were low after nine consecutive doses, and no accumulation was observed. Rifaximin serum levels were minimal and similar to those previously reported in studies of healthy volunteers.

Rifaximin was compared with placebo and ciprofloxacin for treatment of travelers' diarrhea in a randomized, double-blind clinical trial. Adult travelers (N = 399) consulting travel clinics in Mexico, Guatemala, and India were randomized to receive rifaximin 200 mg three times a day, ciprofloxacin (500 mg two times a day and placebo once a day), or placebo three times a day for 3 days. Patients recorded in daily diaries the time and consistency of each stool and documented symptoms for 5 days after treatment. Stool samples were collected for microbiologic evaluations before and after treatment. The median time to last unformed stool (TLUS) in the rifaximin group (32.0 hours) was less than one half that in the placebo group (65.5 hours; P = 0.001; risk ratio 1.6; 95% confidence interval 1.2, 2.2; primary efficacy endpoint). The median TLUS in the ciprofloxacin group was 28.8 hours (P = 0.0003 versus placebo; P = 0.35 versus rifaximin). Rifaximin was less effective than ciprofloxacin for invasive intestinal bacterial pathogens. Oral rifaximin is a safe and effective treatment of travelers' diarrhea caused by noninvasive pathogens.

BACKGROUNDThis double-blind, placebo-controlled study was conducted to assess the efficacy of the nonabsorbed oral antibiotic rifaximin to prevent shigellosis in volunteers challenged with Shigella flexneri.METHODSVolunteers were randomized to receive either prophylactic rifaximin (200 mg 3 times daily for 3 days; n = 15) or placebo (n = 10) on days 0, 1, and 2. On day 1, volunteers were challenged with approximately 1500 colony-forming units of S. flexneri 2a strain 2457T given orally in sodium bicarbonate buffer.RESULTSThe incidence of diarrhea was 0 with rifaximin, compared with 60% with placebo (P = .001). The median time to onset of diarrhea was 78.5 h with placebo (P < .001). The incidence of dysentery was 0 for rifaximin and 10% for placebo (P = .4). The incidence of colonization with Shigella was 0 with rifaximin, compared with 50% with placebo (P < .005). A significant serum or mucosal immune response after challenge by at least 1 indicator (immunoglobulin A titer, immunoglobulin G titer, and immunoglobulin A antibody-secreting cell count) was 0 with rifaximin and 80% with placebo (P < .001).CONCLUSIONSRifaximin was effective and well tolerated, compared with placebo, in preventing shigellosis in this double-blind study of volunteers challenged with S. flexneri 2a.

Acute graft-versus-host disease (AGvHD) is a significant cause of morbidity and mortality in patients receiving a bone marrow transplant from an unrelated donor, and in an effort to reduce this problem, donors are selected for the least possible HLA incompatibility with the recipient. Selection criteria have included minimal incompatibility for the HLA-A, -B, and -DR loci and low reactivity in mixed lymphocyte culture (MLC); however, the value of MLC reactivity for prediction of development of AGvHD has been questioned. We therefore examined the correlation of MLC reactivity with AGVHD in recipients of unrelated bone marrow transplants. Reactivity in the GvH direction was assessed as relative response (RR) of donor lymphocytes to recipient stimulator lymphocytes. In 126 transplanted pairs with technically satisfactory MLC tests, the RR was divided into quartiles (0-1, 2-5, 6-16, and 17-117% RR). HLA-DRB1 incompatibilities were more frequent in the highest quartile (p < 0.001); there were no significant differences among quartiles in donor or recipient age, diagnosis, or frequency of HLA-A or -B incompatibility. Incidence of AGVHD during the first 100 days post-transplant was assessed by Kaplan-Meier analysis. There was no significant difference in incidence of AGvHD among quartiles for the entire group of 126 pairs, for a subset with hematologic malignancy, for a subset selected by a more stringent standard for ''technically satisfactory'' MLC, or for a subset matched for A, B, and DRB1. The MLC response of donor lymphocytes to recipient stimulator lymphocytes is thus not predictive of development of AGvHD in our patient population receiving unrelated donor bone marrow. Since there was no difference in mortality related to high and low MLC responses, our data also suggest that MLC results are not predictive of survival in this population.

Lupus inhibitors have been reported in a number of pathologic states in which there is a disruption of normal immunoregulation. We report here the development of new lupus inhibitors following bone marrow transplantation. Retrospective analysis of 1292 patients undergoing transplantation at the University of Minnesota over a 10 year period demonstrated newly recognized lupus inhibitors in 3% of the patients. These inhibitors were usually detected in the first 1-2 months after transplant. They occurred more frequently in children, with a particularly high incidence in patients with Hurler syndrome. The development of inhibitors was associated with the use of cyclosporine A (CsA) or T depletion for GVHD prophylaxis, with the use of busulfan/cytoxan as a preparative regimen (which includes phenytoin for seizure prophylaxis) and with the occurrence of viral infections. Lupus inhibitors were not associated with development of GVHD, or with any diagnosis other than Hurler syndrome. Thrombotic complications were rare as would be expected in this severely thrombocytopenic population. The incidence of lupus inhibitors that we recognized may substantially underestimate the true incidence as frequent routine coagulation studies were not performed in these patients. Prospective evaluation of lupus inhibitors during bone marrow transplant may provide insight into the pathogenesis of these inhibitors in other disease states.

We performed a prospective, randomized trial in CMV seronegative marrow recipients to determine if filtered blood products were as effective as CMV-seronegative blood products for the prevention of transfusion-transmitted CMV infection after marrow transplant. Before transplant, 502 patients were randomized to receive either filtered or seronegative blood products. Patients were monitored for the development of CMV infection and tissue-documented CMV disease between days 21 and 100 after transplant. Infections occurring after day 21 from transplant were considered related to the transfusion of study blood products and, thus, were considered evaluable infections for the purpose of this trial. In the primary analysis of evaluable infections, there were no significant differences between the probability of CMV infection (1.3% v 2.4%, P = 1.00) or disease (0% v 2.4%, P = 1.00) between the seronegative and filtered arms, respectively, or probability of survival (P = .6). In a secondary analysis of all infections occurring from day 0 to 100 post-transplant, although the infection rates were similar, the probability of CMV disease in the filtered arm was greater (2.4% v 0% in the seronegative arm, P = .03). However, the disease rate was still within the prestudy clinically defined acceptable rate of < or = 5%. We conclude that filtration is an effective alternative to the use of seronegative blood products for prevention of transfusion-associated CMV infection in marrow transplant patients.

Interleukin-1 alpha (IL-1 alpha) can act as both a hematopoietic growth factor and a stimulant of cellular and humoral immune responses. To promote acceleration of hematologic recovery and induce immune antitumor activity, we initiated a phase I/II dose escalation trial of 6-hour daily infusions of recombinant human IL-1 alpha after autologous transplantation. Forty patients with Hodgkin's disease (n = 9) and non-Hodgkin's lymphoma (n = 31) transplanted with unmobilized autologous peripheral blood stem cells or bone marrow stem cells received daily 6-hour infusions of IL-1 alpha (day 0 to day +13) at daily doses between 0.1 to 10 micrograms/m2/d; 7 patients received only 7 planned days of IL-1 alpha (day 0 through 6). Most patients received all 14 days of therapy, although 5 patients discontinued treatment early (after 1 to 6 doses) because of fever and severe chills. Toxicity included IL-1 alpha-related fever (occurring on a median of 9 of 14 treatment days), fatigue, and severe chills. Hypotension was dose-limiting and led to discontinuation of IL-1 alpha in both patients receiving 10 micrograms/m2/d. IL-1 alpha-treated patients receiving 3.0 micrograms/m2/d (the maximum tolerated dose) achieved neutrophil recovery (absolute neutrophil count greater than 500/microL) significantly earlier (median, 12 days; range, 11 to 27) than untreated control patients or those receiving IL-1 alpha at 0.1 to 1.0 micrograms/m2/d (median, 27; range, 9 to 63; P < .0001). In addition, the IL-1 alpha patients' bone marrows at day +14 were significantly enriched with committed myeloid progenitor cells. Strong trends to earlier freedom from red blood cell (P = .06) and platelet (P = .09) transfusions were also noted after IL-1 alpha treatment. This earlier hematopoietic engraftment after 3.0 micrograms/m2/d IL-1 alpha allowed earlier hospital discharge (median, 25 v 37 days for control or low-dose IL-1 alpha patients [P < .0001]) and a concomitant reduction (by $38,000) in median hospital charges (P = .01). The clinical toxicities of IL-1 alpha infusion are substantial, though not life-threatening. The accelerated hematopoiesis and immune response activation observed in this trial suggest the value of its further investigation in controlled trials and perhaps in combination with other hemopoietins after transplantation.

The cellular immunoincompetence which follows bone marrow transplantation (BMT) allows both primary and reactivation infection with herpes viruses. We report the overall incidence and timing of varicella zoster virus (VZV) infections after BMT, including the clinical course, complications and associated clinical risk features. Of 1186 patients undergoing BMT through 1989, 216 patients developed VZV infection between 4 days and 10.8 years after BMT; 86% of them within the first 18 months. Of all patients transplanted, 15 +/- 3% by 6 months and 52 +/- 14% by 5 years had developed VZV infection. Dermatomal zoster represented 62% of the infections, while 32% had complicated VZV infection--CNS, disseminated or visceral zoster. All serious infections occurred within 7 months of BMT but only two patients died, both from VZV pneumonitis. Allogeneic and autologous recipients had a similar incidence of VZV infection. VZV seropositive patients had more frequent, earlier and often more complicated or disseminated infections. Age > or = 10 years and radiation in the pre-transplant conditioning were significantly and independently associated with higher rates of VZV infection within a multivariate regression model. Using this model, we could define clinical risk groups with distinctly different hazards of VZV infection: age > 10 years, radiation pre-BMT and VZV seropositive patients had a 44% incidence by 3 years versus age < 10 years, no radiation and VZV seronegative had a 0% incidence by 3 years. Acyclovir assigned for prophylaxis of CMV or HSV infection had no effect on the timing or incidence of VZV infection.(ABSTRACT TRUNCATED AT 250 WORDS)

We report 12 years’experience with histocompatible, related donor marrow transplantation for 123 patients with acute lymphoblastic leukaemia; 104 second remission. Four regimens were studied: cyclophosphamide (Cy)+total body irradiation (TBI) (n= 35); Cy + fractionated TBI (n= 45); TBI + high‐dose cytarabine (n= 15); and hyperfractionated TBI + Cy (n= 28). 45 patients survive (34 ± 9%: 95% confidence interval) between 1 and 12·7 years (median 7·8 years) following BMT and 29 ± 8% survive leukaemia‐free. Significantly improved disease‐free survival was observed in patients with an initial WBC < 50 x 109/l (P= 0·02). Conditioning regimens tested yielded similar outcomes, though TBI/cytarabine led to greater treatment associated mortality. Leukaemia relapse was the most frequent cause of failure in 56 ± 11%; median time of relapse 8 months following BMT, none beyond 2·2 years. Relapse was more frequent with higher WBC, shorter initial remission and previous CNS leukaemia. Acute and/or chronic GVHD was associated with a strong trend (P= 0·06) towards less relapse. Allogeneic BMT may be curative for a substantial fraction of patients with ALL, but additional anti‐leukaemic measures beyond these conditioning modifications tested will be required to prevent post‐transplant leukaemia recurrence.

PURPOSE Bone marrow transplantation (BMT) for Philadelphia chromosome-positive (Ph1) chronic myelogenous leukemia (CML) results in a 55% to 64% disease-free survival (DFS) rate in 20% to 30% of cases with a matched-sibling donor (MSD). Studies that include primarily adults with CML, using unrelated-donor (URD) BMT, have expanded this option to those without an MSD. We review and compare the efficacy of URD and MSD BMT in children with Ph1 CML. PATIENTS AND METHODS Eleven children with URD BMTs were reviewed and compared with 11 children with MSD BMTs for Ph1 CML. Among the URD BMT recipients, there were three with fully matched marrows and 10 with advanced CML. The median time from diagnosis to transplant was 2.6 years. Among the MSD BMT recipients, 11 had fully matched marrows and five had advanced CML. The median time from diagnosis to BMT was 0.7 years. All received non-T-depleted marrows after cyclophosphamide and fractionated total-body irradiation. RESULTS Both groups had similar engraftment times. Late graft failure occurred in two URD patients. Graft-versus-host disease (GVHD), > or = grade II, was similar in both groups (77% for URD BMT, 45% for MSD BMT), although more severe acute disease and more persistent chronic disease was seen in the URD group. The Kaplan-Meier estimate of DFS was 45% +/- 15% (SE) and 78% +/- 14% (SE) in the URD and MSD groups, respectively, at 3 years. All had Karnofsky scores of more than 70%, except one URD patient debilitated from GVHD. CONCLUSION CML is eventually fatal to all patients without BMT. The high survival rate seen among children who receive a URD BMT, despite several adverse factors, opens this important therapeutic option to those without an MSD.

We have recognized a rapidly progressive, often fatal shock syndrome associated with viridans streptococcal sepsis following bone marrow transplantation (BMT). Of 832 patients receiving a marrow transplant at the University of Minnesota between 1976 and 1988, including 123 with viridans streptococcal bacteremia, 10 patients (8%) developed clinical shock within an average of 2 days (range 0-4 days) of their first positive blood culture. Viridans streptococcal shock occurred in patients early in the transplantation course, between 1 and 28 (median 6) days following BMT when all 10 patients were neutropenic. Six of the 10 patients died as a consequence of their shock or from subsequent complications. The most frequent (6 of 10 patients) viridans streptococcal species isolated in the shock patients was Streptococcus mitis. Of multiple factors analyzed for increased risk of developing viridans streptococcal shock, only younger patient age was significantly associated with the development of shock. Although 58% of BMT recipients with viridans streptococcal bacteremia were younger than 15 years, all 10 patients comprising the shock population were < 15 years of age (P < 0.02). We speculate that certain streptococcal strains may trigger fulminant shock in the immunocompromised BMT patient.

Cytomegalovirus pneumonia complicated bone marrow transplantation in 75 (63 allogeneic and 12 autologous) of 1136 recipients (Kaplan-Meier incidence 8.8%). CMV pneumonia occurred more frequently in allogeneic (12.4%) than autologous recipients (3.3%). Increased risk for CMV pneumonia was observed in allogeneic recipients who were seropositive (relative risk = 2.9), older age (RR = 1.4 per decade), those conditioned with total-body irradiation (RR = 2.7), who received antithymocyte globulin (RR = 2.9) or T cell-depleted marrow (RR = 2.7) or who had CMV viruria (RR = 4.0) or viremia (RR = 5.9). Autologous recipients were also at increased risk if they were seropositive (RR = 6.1), or developed viruria (RR = 7.0) or viremia (RR = 15.4). Thirteen of 14 untreated patients died without improvement. Prognosis was poor in patients who were ventilator-dependent at initiation of therapy (median survival 17 days), with only 1 long-term survivor. In contrast, patients ventilator-independent at initiation of therapy with ganciclovir and immunoglobulin (n=22) had a median survival of >274 days, with 9 long-term survivors. Ganciclovir alone or acyclovir with immunoglobulin in ventilator-independent patients was less effective (median survivals 80 and 10 days, respectively). Overall, 10 of 75 patients were surviving 1073 months (median 47) from diagnosis; 9 of these were ventilator-independent at initiation of therapy and received ganciclovir with immunoglobulin. CMV pneumonia was less common, but was severe in autologous recipients, with only 2 of 12 surviving. CMV pneumonia remains a prominent cause of death following BMT. Early therapy with ganciclovir and immunoglobulin before respiratory failure supervenes may improve survival.

BACKGROUND:We developed a test to discern small numbers of residual leukemic progenitor cells in the bone marrow of patients with acute lymphoblastic leukemia (ALL) in remission. Preliminary studies revealed that before undergoing bone marrow transplantation such patients differed in their burden of leukemic progenitor cells. These observations suggested that the burden of these cells might influence the risk of relapse after transplantation. METHODS:The number of residual leukemic progenitor cells before bone marrow transplantation was determined for 83 patients with high-risk ALL. We combined multiparameter flow cytometry and cell sorting with assays for leukemic progenitor cells in a quantitative method for the detection of minimal residual disease. RESULTS:The count of leukemic progenitor cells in bone marrow specimens from patients in remission varied markedly between patients, ranging from 0 to 12,546 cells per million mononuclear cells, or from 0 to 1.255 percent (median, 51 leukemic progenitor cells per million mononuclear cells, or 0.005 percent). Patients whose count of leukemic progenitor cells exceeded the median value had a higher likelihood of relapse than did patients with values below the median (relapse rate at one year, 100 percent vs. 41 percent; P < 0.001). There was a statistically significant inverse relation between the leukemic progenitor-cell content of bone marrow before transplantation and the duration of remission after transplantation (P < 0.001). The estimated risk of relapse for patients with > or = 51 leukemic progenitor cells per million mononuclear cells was more than 3.5 times the risk for patients with lower counts, after adjustment for the effects of other covariates (P = 0.005). CONCLUSIONS:The count of residual leukemic progenitor cells is a powerful predictor of relapse after autologous bone marrow transplantation, particularly among male patients. Its measurement may be useful for analyzing and improving the treatment of patients with high-risk ALL in remission.

Fourteen patients with high-risk B-lineage acute lymphoblastic leukemia (ALL) in complete remission underwent autologous bone marrow transplantation (BMT) using a combined immunochemopurging protocol. A monoclonal antibody (MoAb) cocktail of BA-1, BA-2, and BA-3 plus rabbit complement (C′) plus 4-hydroperoxycyclophosphamide (4-HC) was used to eliminate residual occult leukemia cells from autografts. All patients were conditioned with single-dose total body irradiation (TBI) followed by high-dose Ara-C. All 14 patients engrafted at a median of 24 days (range, 12 to 36 days). Three patients are alive and disease free at 3.5 years, 3.9 years, and 4.1 years post-BMT. The Kaplan-Meiser estimate and standard error of the probability of sustained remission was 23% +/- 12% at 3.5 years post-BMT with a mean relapse-free interval of 1.4 +/- 0.4 years. The disease-free survival (DFS) at 3.5 years was 21% +/- 11%, with a mean DFS time of 1.3 +/- 0.4 years. A novel and quantitative minimal residual disease (MRD) detection assay, which combines fluorescence-activated multiparameter flow cytometry and cell sorting with leukemic progenitor cell (LPC) colony assays, was used to analyze remission BM samples from B-lineage ALL patients for residual LPC, and to evaluate the efficacy of ex vivo BM purging. Notably, the minimal residual leukemia burden before BMT, as measured by the percentage of B-lineage LPC in the pre-BMT remission BM samples, indicated the outcome of the BMT. The median value for the minimal residual leukemia burden before BMT was 0.0035% (35 LPC/10(6) mononuclear cells). The Kaplan-Meier estimates and standard errors of the probability of remaining in remission after BMT were 43% +/- 19% for patients whose BM samples contained less than or equal to 0.0035% LPC and 0% +/- 0% for patients whose BM samples contained greater than 0.0035% B-lineage LPC (P less than .05). In contrast to the minimal residual leukemia burden measured by the described MRD assay system, the percentage of blasts or TdT+ cells in the remission BM samples did not correlate with the probability of relapse. The applied purging protocol showed variable success in destroying target B-lineage LPC populations contaminating the autografts. While in some cases purging was highly effective, eliminating up to greater than or equal to 4 logs of residual B-lineage LPC, in other cases only 0.1 to 0.2 logs of B- lineage LPC were purged.(ABSTRACT TRUNCATED AT 400 WORDS).

We studied the incidence, outcome and risk factors for systemic Candida infection in 665 recipients of allogeneic, syngeneic and autologous bone marrow transplantations (BMT) between 1979 and 1987. Systemic Candida infection, defined as occurrence of one or more positive blood or CSF cultures for Candida sp., or presence of Candida sp. in culture or biopsy of deep tissue, was detected in 76 patients (12.5%) in the first year following BMT. Candida infection was independently associated with increasing age (p less than 0.0001), detection of one or more positive surveillance cultures for Candida sp. (p less than 0.0001), increased duration of granulocytopenia (p = 0.0005) and total body irradiation as part of the preparative regimen compared with chemotherapy only or chemotherapy and total lymphoid irradiation (p = 0.02). Other patient characteristics including underlying disease, origin of graft, recipient sex, graft-versus-host disease (GVHD) prophylaxis and occurrence of acute GVHD or chronic GVHD were not independently associated with Candida infection following BMT: 60/76 patients with Candida infections have died, and in 19/60 cases death could be directly attributed to Candida infection. Awareness of the serious nature and the risk features for Candida infections may be useful in developing strategies of prevention and treatment.

From 1983 to 1989 we performed a prospective trial of 70 consecutive, in vitro purged autologous bone marrow transplants (BMT) for patients with progressive non-Hodgkin's lymphoma. Forty-nine patients had responsive disease at the time of transplantation while 21 others had refractory high risk lymphoma. Forty-two patients with B-lineage lymphoma received autologous marrow purged in vitro with monoclonal antibody (anti CD9, CD10, CD24) plus complement, 12 with T-lineage lymphoma received monoclonal antibody immunotoxins (anti CD5, CD7-ricin conjugates) along with 4-hydroperoxycyclophosphamide purging and 16 received unpurged marrow. All received cyclophosphamide, 57 with fractionated total body irradiation, and 13 with BCNU and cytarabine. Hematologic engraftment was prompt and unaffected by phenotype (B vs. T) or by in vitro purging used (B vs. T vs. none) although nine of 16 non-relapse deaths were related to poor graft function. Fifty-one patients (73%) were alive in complete remission (CR) 1 month following transplantation while 15 patients (12 with initially refractory disease) had persistent disease. Subsequently, 41 +/- 18% (by Kaplan-Meier estimate; +/- 95% confidence limits) of those who achieved CR remained relapse free 1-6.4 (median 3) years post-BMT. Neither risk group, purging, nor immunophenotype predicted subsequent post-transplant relapse. Among those 51 who achieved CR, 13 of 43 (27 +/- 14%) with responsive disease survive disease free while three of eight (38 +/- 34%) refractory patients survive disease free (p = 0.96). Overall, 24 patients survive, 16 in continuous complete remission 1-6.5 years following transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

The radiobiologic features of primary clonogenic blasts (referred to also as T-lineage leukemic progenitor cells) from newly diagnosed and relapsed T-lineage acute lymphoblastic leukemia (ALL) patients were analyzed. Intrinsic radiation sensitivity differed substantially among primary clonogenic blasts from 34 newly diagnosed patients. The mean D0 (37% dose slope), SF2 (surviving fraction at 200 cGy), and alpha values (initial slope of the survival curve) were 141 +/- 15 cGy, 0.31 +/- 0.04, and 0.630 +/- 0.093 Gy-1, respectively. Among newly diagnosed cases, nine had SF2 values of greater than or equal to 0.50 and alpha values of less than or equal to 0.2 Gy-1, consistent with a marked intrinsic radiation resistance at the level of clonogenic blasts using the multitarget and linear quadratic models of cell survival. Of these nine radiation resistant cases, seven were CD3+. Furthermore, the mean D0 (162 +/- 20.8 cGy) and SF2 (0.377 +/- 0.057) values for the 20 CD3+ cases were significantly higher than the D0 (108.6 +/- 18.2 cGy) and SF2 (0.204 +/- 0.051) values for the 14 CD3- cases (P less than or equal to .05). Thus, clonogenic blasts from CD3+ newly diagnosed T- lineage ALL patients were more resistant to radiation than clonogenic blasts from CD3- newly diagnosed T-lineage ALL patients. Nineteen T- lineage ALL patients received autologous bone marrow transplants during complete remission. Pretransplant conditioning consisted of total body irradiation (TBI) combined with high-dose chemotherapy. Primary clonogenic blasts from patients who relapsed after bone marrow transplantation (BMT) displayed a particularly high degree of intrinsic radiation resistance with a mean D0 value of 333 cGy and an alpha value of 0.112 Gy-1. The expression of CD3 antigen appeared to predict the outcome of relapsed T-lineage ALL patients undergoing autologous BMT after TBI plus high-dose chemotherapy. The Kaplan-Meier estimates and standard errors of the probability of remaining in remission after BMT were 60% +/- 22% (mean relapse - free interval = 1.6 +/- 0.7 years) for CD3- patients and 0% +/- 0% (mean relapse - free interval = 0.2 +/- 0.0 years) for CD3+ patients (P = .002). Furthermore, the mean percentage of CD3-positive leukemic marrow blasts at presentation or relapse before BMT was significantly lower than the mean percentage of CD3- positive leukemic marrow blasts at relapse after BMT. Notably, in cultured leukemic bone marrow specimens from newly diagnosed as well as relapsed patients, colony blasts surviving in vitro radiation expressed CD3 more vividly than did colony blasts in unirradiated cultures.(ABSTRACT TRUNCATED AT 400 WORDS)