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Biomedical subjects

D C Roy

Publications and source records attributed to D C Roy.

At least 19 recordsLinked to original sources
PubMed1992

Tolerance to host minor histocompatibility antigens after allogenic bone marrow transplantation. Specific donor-host unresponsiveness is maintained by peripheral tolerizing cells.

The development of graft-host tolerance after allogeneic bone marrow (BM) transplantation is more demanding than the acquisition of self-tolerance because both donor-derived mature T cells and immature thymocytes encounter host Ag. The mechanism involved in tolerization of mature T cells, contained in unmanipulated BM, remains undefined. In previous experiments, we showed in vivo unresponsiveness to host minor histocompatibility Ag (MiHA) in immunocompetent chimeras obtained after MiHA-incompatible BM transplantation. In this study, we wanted to determine: first, what was the specificity of this graft-host unresponsiveness, and second, whether peripheral cells were involved in tolerization? LP recipients were irradiated (9, 5 Gy), injected with 10(7) undepleted BM cells from B10 donors and studied 100 to 150 days later. (B10-->LP) chimeras were immunized in vivo and restimulated in vitro with cells displaying one or multiple incompatible MiHA. In bulk culture experiments, chimeras demonstrated specific CTL unresponsiveness to host MiHA but responded normally to third party MiHA. In limiting dilution analysis conditions, chimeras showed a profound deficit, but not a complete absence of anti-host CTL precursor. Studies with congenic stimulators/targets showed that graft-host tolerance was induced against both immunodominant (e.g., H-3.2) and nonimmunodominant (e.g., H-8.2) MiHA although at the CTL precursor level, it was more complete against the former. Furthermore, chimera spleen cells inhibited the generation of CTL activity against host- and donor-type MiHA but not against third party Ag. This specific suppressor activity was not T cell dependent, and was mediated by radiosensitive cells that are not found in freshly explanted organs from normal mice. Taken together, our results suggest that peripheral tolerization can be a remarkably efficient process to maintain tolerance to MiHA after BM transplantation. Thus, peripheral tolerizing mechanisms may contribute not only to the induction of tolerance to Mls superantigens or to the product of transgenes (if expressed at high levels) but also to a wide array of MiHA.

Animals↗
PubMed1991

Immunologic purging of marrow assessed by PCR before autologous bone marrow transplantation for B-cell lymphoma.

BACKGROUND: The use of autologous bone marrow transplantation is increasing in the management of advanced cancers. Many investigators have attempted to "purge" autologous marrow of residual tumor cells because of concern that reinfused tumor cells might contribute to relapse. The efficacy of purging remains unproved. METHODS: We performed clonogenic assays in a tumor cell line in culture to determine the efficiency of immunologic purging. Amplification by the polymerase chain reaction (PCR) was used to detect residual lymphoma cells before and after purging of bone marrow from 114 patients with B-cell non-Hodgkin's lymphoma in whom a translocation (t(14;18] that could be amplified by PCR was detected at the time of their initial evaluation. RESULTS: Immunologic purging in vitro resulted in a 3-to-6-log destruction of cells in the tumor cell line. Residual lymphoma cells were detected by PCR in the bone marrow of all patients before purging. No lymphoma cells could be detected in the marrow of 57 patients after purging. Disease-free survival was increased in these 57 patients as compared with those whose marrow contained detectable residual lymphoma (P less than 0.00001). The ability to purge residual lymphoma cells was not associated with the degree of bone marrow involvement (P = 0.4494) or the previous response to therapy (P = 0.1298). CONCLUSIONS: The inability to purge residual lymphoma cells was the most important prognostic indicator in predicting relapse. These results provide evidence of the clinical usefulness of ex vivo purging of autologous bone marrow in the treatment of patients with lymphoma and suggest that the reinfusion of malignant cells in autologous marrow contributes to relapse

Antibodies, Monoclonal↗
PubMed1991

Anti-MY9-blocked-ricin: an immunotoxin for selective targeting of acute myeloid leukemia cells.

The use of immunotoxins (IT) to selectively destroy acute myeloid leukemia (AML) cells in vivo or in vitro is complicated by both the antigenic similarity of AML cells to normal progenitor cells and the difficulty of producing a sufficiently toxic conjugate. The monoclonal antibody (MoAb) anti-MY9 is potentially ideal for selective recognition of AML cells because it reacts with an antigen (CD33) found on clonogenic AML cells from greater than 80% of cases and does not react with normal pluripotent stem cells. In this study, we describe an immunotoxin that is selectively active against CD33+ AML cells: Anti-MY9-blocked-Ricin (Anti-MY9-bR), comprised of anti-MY9 conjugated to a modified whole ricin that has its nonspecific binding eliminated by chemical blockage of the galactose binding domains of the B-chain. A limiting dilution assay was used to measure elimination of HL-60 leukemic cells from a 20-fold excess of normal bone marrow cells. Depletion of CD33+ HL-60 cells was found to be dependent on the concentration of Anti-MY9-bR and on the duration of incubation with IT at 37 degrees C. More than 4 logs of these leukemic cells were specifically depleted following short exposure to high concentrations (10(-8) mol/L) of Anti-MY9-bR. Incubation with much lower concentrations of Anti-MY9-bR (10(-10) mol/L), as compatible with in vivo administration, resulted in 2 logs of depletion of HL-60 cells, but 48 to 72 hours of continuous exposure were required. Anti-MY9-bR was also shown to be toxic to primary AML cells, with depletion of greater than 2 logs of clonogenic cells following incubation with Anti-MY9-bR 10(-8) mol/L at 37 degrees C for 5 hours. Activity of Anti-MY9-bR could be blocked by unconjugated Anti-MY9 but not by galactose. As expected, Anti-MY9-bR was toxic to normal colony-forming unit granulocyte-monocyte (CFU-GM), which expresses CD33, in a concentration- and time-dependent manner, and also to burst-forming unit-erythroid and CFU-granulocyte, erythroid, monocyte, megakaryocyte, although to a lesser extent. When compared with anti-MY9 and complement (C'), Anti-MY9-bR could be used in conditions that provided more effective depletion of AML cells with substantially less depletion of normal CFU-GM. Therefore, Anti-MY9-bR may have clinical utility for in vitro purging of AML cells from autologous marrow when used at high IT concentrations for short incubation periods. Much lower concentrations of Anti-MY9-bR that can be maintained for longer periods may be useful for elimination of AML cells in vivo.

Acute Disease↗
PubMed1990

Natural history of mixed chimerism after bone marrow transplantation with CD6-depleted allogeneic marrow: a stable equilibrium.

Mixed hematopoietic chimerism (MC) is a common finding after allogeneic bone marrow transplantation (BMT), but the natural history of this phenomenon remains unclear. To understand the evolution and the implications of this finding, we performed a prospective analysis of the development of mixed chimerism in 43 patients with hematologic malignancies who received bone marrow (BM) from human leukocyte antigen (HLA)-identical sibling donors. T-cell depletion in vitro with anti-T12 (CD6) monoclonal antibody and rabbit complement was used as the only method of graft-versus-host disease (GVHD) prophylaxis. Overall, MC was identified in peripheral blood (PB) and BM in 22 of 43 (51%) patients evaluated. MC was found by restriction fragment length polymorphism (RFLP) analysis in 21 of 40 (53%) patients, by cytogenetic analysis in 6 of 29 (21%) patients, and by red blood cell phenotyping in 4 of 9 (44%) patients. RFLP studies were performed at 0.5, 1, 3, 6, 9, and 12 months post-BMT and then every 6 months, and showed a high probability of developing MC in the first 6 months after BMT followed by stabilization after 12 months. Cytogenetic analysis was less sensitive in detecting MC. Once MC was detected after BMT, the percentage of recipient cells increased very slowly over more than 3 years of follow-up, and no patient reverted to complete donor hematopoiesis (CDH). Thus, recipient and donor cells remained in a relative state of equilibrium for prolonged periods that seemed to favor recipient cells over donor cells. Patient's disease, remission status, or intensity of the transplant preparative regimen did not influence the subsequent development of mixed chimerism. Early immunologic reconstitution was the only factor that correlated with the subsequent chimeric status of the patients. The percentage and absolute number of T3 (CD3) and T4 (CD4) positive cells at day 14 after BMT were significantly higher in the patients who maintained CDH but NK cell reconstitution was similar in both groups, suggesting that early reconstitution with T cells may play a role in preventing recovery of recipient cells after BMT. GVHD was also associated with maintenance of CDH, but the probability of relapse, survival, and disease-free survival was identical in patients with MC and CDH.

Antigens, CD↗
PubMed1990

Comparative activities of rabbit complements of different ages using an in-vitro marrow purging model.

In order to determine the best time to obtain complement for use in marrow purging in vitro, we have used 51Cr-release and limiting dilution assays (LDA) to evaluate the ability of serum from rabbits 20-30 (25d), 30-40 (35d) and 40-50 (45d) days old to lyse a series of neoplastic target cells in the presence of complement activating antibodies. Utilizing a limiting dilution assay (LDA) to measure log depletion of tumor cells in a 20-fold excess of normal bone marrow, treatment with monoclonal antibody and 25d complement depleted at least 4 logs of leukemia or lymphoma cells. 35d and 45d complements were approximately one log less effective. When normal bone marrow alone was treated with either J5 (CD10) antibody alone, each complement alone or a combination of J5 antibody with each complement, there was no significant depletion of hematopoietic progenitors in any subgroup. These results suggest that complement from 20-30 day old rabbits should be used for the purpose of ex-vivo purging due to its highly sensitive and specific activity.

Age Factors↗
PubMed1986

Oesophago-pleuro-cutaneous fistula.

We describe a case of oesophago-pleuro-cutaneous fistula occurring as a complication of tuberculous pyopneumothorax in a young adult.

Adolescent↗
PubMed1978

A comparison of physical efficiency between Indian physical education and medical students.

The recovery pulse and respiration were analysed to determine the level of physical fitness among the physical education and medical students of Banaras Hindu University. The analysis of the data suggested that physical fitness as measured by recovery rate was better in physical education students than in medical students. Following questionnaire method, it has been noted that the daily activity of physical education students was more than the medical students and probably the reason for higher efficiency in them.

Adult↗
PubMed1976

5-year follow-up of cytotoxic chemotherapy as an adjuvant to surgery in carcinoma of the bronchus.

This report gives the 5-year findings of a double-blind study of long-term cytotoxic chemotherapy as an adjuvant to surgery in patients receiving busulphan or cyclophosphamide for carcinoma of the bronchus compared with a group receiving a placebo. Of 243 patients initially allocated busulphan, 234 cyclophosphamide and 249 placebo, 28%, 27% and 34% respectively were alive at 5 years. There were significant associations between mortality from bronchial carcinoma and histological involvement of the resected intrathoracic nodes and the histology of the tumour. Haematological toxicity, especially thrombocytopenia, was frequent and severe in the busulphan series, and low platelet counts continued long after chemotherapy was stopped.

Bronchial Neoplasms↗
PubMed1976

An investigation of the chest radiographs in a controlled trial of busulphan, cyclophosphamide, and a placebo after resection for carcinoma of the lung.

A standard series of radiographs of 588 patients allocated at random to treatment with busulphan (B patients), cyclophosphamide (C patients), or a placebo (P patients) for two years after surgery for bronchial carcinoma were viewed in three stages (following procedures which avoided bias) by an independent assessor, unaware of the allocated treatment of any patient, with a view to identifying pulmonary changes due to busulphan. Radiographic appearances consistent with busulphan lung were not reported in any of the 195 B patients (receiving a mean dosage of 464 mg of busulphan over 301 days) or of the 192 C patients but were present in one of the 201 patients receiving placebo.

Bronchial Neoplasms↗