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Biomedical subjects

J F Bach

Publications and source records attributed to J F Bach.

At least 181 records · Page 10Linked to original sources
PubMed1993

Role of CD4+CD45RA+ T cells in the development of autoimmune diabetes in the non-obese diabetic (NOD) mouse.

The non-obese diabetic (NOD) mouse spontaneously develops a T cell-mediated autoimmune disease, sharing many features with human insulin-dependent diabetes mellitus (IDDM), leading to insulin-secreting beta cell destruction. The role of CD4+ T cells has been evidenced at two levels. First, CD4+ T cells from diabetic animals are required to transfer diabetes to non-diabetic recipients in conjunction with CD8+ effector T cells. Second, suppressive CD4+ T cells have been characterized in non-diabetic NOD mice. T cells with different functions can thus share the CD4+ phenotype. Since CD4+ T cells can be divided into at least two subgroups on the basis of CD45 isoform expression, we evaluated the distribution of CD4+ T cells expressing the CD45RA isoform on NOD mouse thymocytes and peripheral T cells. The percentage of CD45RA+ cells was dramatically increased among the most mature CD3bright thymocytes and among CD4+ T cells in lymph nodes of the NOD mouse as compared with control strains. This increase was related to the development of insulitis. Interestingly, the CD45RA isoform was expressed on most CD4+ T cells invading the islets. In vivo treatment with an anti-CD45RA mAb prevented the development of insulitis and spontaneous diabetes in female animals but not the transfer of diabetes by T cells collected from diabetic NOD donors. These results indicate that anti-CD45RA mAb is only effective if given before the full commitment of effector T cells to the destruction of islet beta cells. Thus CD4+CD45RA+ T cells play a key role in early activation steps of anti-islet immunity.

Animals↗
PubMed1993

Implications of de novo ELAM-1 and VCAM-1 expression in human cardiac allograft rejection.

Both cytokines produced by activated monocytes and T cells and direct cell-to-cell contact with antigen-primed T cells during inflammatory reactions are known to induce the expression of several adhesion proteins on endothelial cells. In this prospective longitudinal study, we analyzed the expression of ELAM-1, VCAM-1, and ICAM-1 on myocardial allograft biopsy specimens taken from 16 cardiac allograft recipients either for routine monitoring or for the investigation of suspected rejection. Infiltrating T cells were identified using anti-CD3 antibodies. Three to six sequential biopsies taken at one-week intervals were analyzed by means of conventional histology and immunohistochemistry. Seven patients did not develop rejection during the study; their biopsies were negative for VCAM-1 and ELAM-1, although faint ICAM-1 staining was present on capillaries, reflecting constitutive expression. Three patients entered the study with clear-cut clinical and histologic signs of acute rejection. Intense VCAM-1 and ICAM-1 expression was detected on capillary and postcapillary venules, together with a heavy CD3+ T cell infiltrate; VCAM-1 was also expressed on arteriolar endothelial cells. ELAM-1 was undetectable in all three cases. Six patients developed acute rejection during the course of the study. In four, ELAM-1 and VCAM-1 were expressed on both capillary and postcapillary venules one or two weeks before the histological diagnosis of rejection (heavy CD3+ cell infiltrate). Importantly, ELAM-1 expression was short-lived and had disappeared by the time CD3+ cellular infiltrate was detected, thus extending in vivo the finding that ELAM-1 expression is usually transient in vitro. Only VCAM-1 expression was observed in the other two patients, one week prior to the histological diagnosis of rejection. These results suggest that ELAM-1 and VCAM-1 might represent early predictive markers of acute cardiac allograft rejection. ELAM-1 expression is, however, usually transient, necessitating frequent testing.

Adolescent↗
PubMed1993

Characterization of the extracellular matrix-containing giant perivascular spaces in the NOD mouse thymus.

It is well established that the NOD mouse develops T-cell-dependent autoimmune type I diabetes that is abolished by neonatal Tx and enhanced by Tx at weaning. In a previous study, we demonstrated that the NOD thymus displays various abnormalities in the microenvironmental compartment, including abnormal distribution of epithelial cell subsets, precocious decline in thymic hormone production and formation of giant PVS. These latter structures present an internal ECM-containing network filled with T-cells and to a lesser extent B-cells. Herein we have investigated further the giant PVS and particularly the origin of the T-cells that colonize these structures. The thymic origin of intra-PVS T-cells was ascertained by distinct protocols. First, sublethal X-ray irradiation or HC treatment leading to cortical thymocyte depletion showed that intra-PVS lymphocytes were resistant, similar to medullary thymocytes. Second, adoptive transfer experiments that used newborn or adult irradiated Thy-1 congenic recipients demonstrated that intra-PVS accumulation of T-cells did not result from the reentry of peripheral mature T-cells into the thymus. Third, kinetic studies that used BrdUrd pulse chase revealed that labeled intra-PVS cells appear late, simultaneously with medullary thymocytes, and remain only transiently within the PVS. Thus, the kinetics of T-cell reconstitution of PVS was compatible with the progressive differentiation of T-cell precursors originating from the thymic cortex. In this respect, the giant PVS of the NOD mouse thymus may represent a useful model to study the relationships between trafficking thymocytes and ECM proteins.

Animals↗
PubMed1993

Aberrant distribution of CD4 and CD8 lymphocyte subsets in recent-onset IDDM patients. Effect of cyclosporin.

The monoclonal antibodies 2H4 and 4B4 are specifically directed against CD45RA and CD29 antigens, respectively, which are expressed on both CD4+ and CD8+ lymphocytes. We used them to monitor the distribution of these T-cell subsets in 19 recent-onset IDDM patients (26 +/- 7 yr of age [mean +/- SD throughout]) receiving cyclosporin, and who had been treated with insulin for < 1 mo. Blood samples were examined before starting cyclosporin and after 3 and 9-12 mo of therapy. CD45RA and CD29 are expressed on distinct subsets of CD4+ T-cells, whereas in both healthy subjects and IDDM patients, 2H4 and 4B4 labeling does not always differentiate two distinct CD8+ populations. Various proportions of double-labeled CD8+ CD45RA+ CD29+ cells were detected in 59% of IDDM patients and 70% of healthy control subjects. Before cyclosporin treatment, recent-onset IDDM patients had a significantly lower proportion of CD4+CD29+ cells than the healthy control subjects (42 +/- 11 vs. 52 +/- 9%, P < 0.004). This imbalance corresponded to a significant increase in the CD4+ CD45RA+/CD4+ CD29+ ratio in the IDDM patients (1.37 +/- 0.93 vs. 0.78 +/- 0.36, P < 0.014). Independent of the presence of double-labeled cells, the proportion of CD8+ lymphocytes expressing CD45RA was significantly higher in the patients than in control subjects (72 +/- 15 vs. 57 +/- 15%, P < 0.004). The mean density of the CD45RA antigen (but not that of CD29) on both CD4+ and CD8+ cells was significantly higher in the IDDM patients before treatment than in the healthy control subjects. Cyclosporin induced complete or partial remission of the disease in 12 of 19 patients at 4-6 mo of treatment, but did not correct the imbalance between the regulatory T-cell subsets, regardless of clinical effectiveness. Cyclosporin use was associated with a significant decrease in CD45RA antigen density on both CD4+ and CD8+ T-cells.

Adult↗
PubMed1993

Hypersensitivity to insulin during remissions in cyclosporin-treated IDDM patients.

OBJECTIVE: To test the sensitivity to insulin in recent-onset IDDM patients, its course according to treatment, and the advent of remissions. RESEARCH DESIGN AND METHODS: The euglycemic hyperinsulinemic clamp was used in 54 recent-onset IDDM patients and 14 healthy control subjects. Patients were tested after 1,2, and 4 wk of treatment with either insulin or insulin plus cyclosporin A, during cyclosporin A-associated long-lasting remissions, and during relapses. RESULTS: Insulin sensitivity was markedly decreased in all patients at onset. It was rapidly restored by insulin therapy, whether immunosuppression was associated with it or not. Insulin sensitivity was even higher than normal in the remission patients, who also were characterized by the reappearance of some endogenous insulin secretion and the sustained normalization of blood glucose profiles. During relapses, the deterioration of the blood glucose profiles was associated with some loss of insulin sensitivity. CONCLUSIONS: Cyclosporin A-associated remissions represent an original situation that associates euglycemia with the persistence of low endogenous insulin secretion. Cyclosporin A by itself had no influence on sensitivity to insulin, but allowed the reappearance of some insulin secretory capacity that contributed, with the improvement of insulin sensitivity, to the development of the diabetes honeymoon. The secretion of endogenous insulin, although lower than normal, was sufficient to secure a high sensitivity to insulin and the maintenance of normal blood glucose profiles, presumably because of the fact that insulin was released directly into the portal vein in these conditions. This metabolic state was precarious: the optimal sensitivity to insulin disappeared in patients who relapsed. These results have important clinical consequences: the preservation of islet residual secretory capacity by the use of newer nontoxic immunosuppressive protocols, combined with a minimal supportive insulin therapy in remission patients, may prolong remissions and maintain an optimal insulin sensitivity.

Adult↗
PubMed1993

Automation of large-scale HLA oligotyping using a robotic workstation.

The ability to amplify specific genomic segments by the PCR has made the analysis of DNA polymorphism with oligonucleotidic probes a practical approach to HLA class II typing. However, to make this method more accurate and applicable to large-scale typing, technical and logistic limitations must be overcome and the risk of human errors must be reduced. To address this problem, we developed an automated procedure, using the Biomek 1000. The system consists of a workstation with a robotic arm and an instrument tablet, an electronic interface unit and an IBM PC. It was modified by the addition of a dot-blot apparatus. Automatic preparation of 96 samples for simultaneous DNA amplification is possible, together with PCR product dilution, distribution and dot-blotting. The robot prevents sample contamination, eliminates human errors and reduces operating costs by decreasing the working time by 50%. Thus, the system is suitable for routine analysis, and it also improves typing accuracy. Furthermore, this system can be adapted for a variety of new DNA-typing strategies that require an initial DNA amplification step.

Alleles↗
PubMed1993

HLA genetic heterogeneity of hepatitis B vaccine response in hemodialyzed patients.

Major histocompatibility complex (MHC) determinants are critical to the induction or suppression of immune response and have been shown to control the ability to produce antibodies in response to protein antigen. Hepatitis B vaccine commonly fails among patients with renal failure, but genetic factors that modulate response to this vaccination are not yet characterized. The availability of HLA Class II genotyping by hybridization with specific oligonucleotidic probes, following DNA amplification by the polymerase reaction (PCR), has made the analysis of HLA class II loci a reliable and practical approach. Antibody response to HBs and HLA class II oligotyping were assessed among 203 hemodialyzed patients having received a full course of vaccination. Twenty-two percent (N = 45) produced less than 10 IU (radioimmunoassay) of anti-HBs antibodies following the fourth injection. These nonresponder patients had a significantly decreased frequency of the DR2 haplotype compared to responder patients or to a group of 405 normal controls (8.9% vs. 21.5% and 26.2%, P < 0.01). The frequency of the DR3 haplotype was not increased among subjects with lower response. No significant difference appeared in the responder group. These results argue in favor of the presence of HLA-linked immune response gene(s) controlling humoral response to HBs antigen, rather than in favor of the presence of an immune suppressive gene.

Adult↗
PubMed1993

Xenotransplantation: baboons as potential liver donors? Scientific and ethical issues.

The dramatic development of liver transplantation compared to a relative shortage of donors has brought a renewed interest to xenotransplantation. Because of anatomical and immunological compatibilities, nonhuman primates are the most appropriate donors. The aim of this work was to analyze the different problems of a baboon-to-man liver xenotransplantation. Thirty baboons bred in a French Primatology Center were studied. The analysis of anatomical, microbiological, and immunological data showed that only 8 baboons out of 30 were suitable as donors for xenotransplantation. Considering these data and the ethical issues, the actual feasibility of xenotransplantation programs is discussed.

Animals↗