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Biomedical subjects

J F Bach

Publications and source records attributed to J F Bach.

807 records · Page 45Linked to original sources
PubMedDate not supplied

Latent hepatitis B virus (HBV) infection in systemic necrotizing vasculitis.

We have investigated hepatitis B virus (HBV) infection in systemic necrotizing vasculitis (SNV). Our approach included the detection of the viral surface antigen (HBsAg) with a radioimmunoassay employing monoclonal anti-HBs (m-RIA); in addition, HBV DNA was looked for in serum and peripheral mononuclear blood cells. Among 28 subjects with SNV, 12 were found to be positive for HBsAg with the conventional test (p-RIA) and 7 additional subjects had anti-HBc and/or anti-HBs. From the 16 HBsAg negative individuals, 9 had HBsAg epitopes identified in serum with the m-RIA test and 1 had a low amount of circulating viral DNA. In contrast, only 1 among 6 subjects with other systemic vasculitis showed a positive test for m-RIA and HBV DNA assays; this individual had acquired HIV infection through transfusions which were also probably the source of his HBV infection. HBV DNA sequences were identified in peripheral mononuclear blood cells of 9 from the 37 tested, including 2 individuals who were HBsAg positive only with m-RIA. Therefore, our study indicates a much higher rate of HBV infection in patients with polyarteritis nodosa than previously suspected.

Antibodies, Monoclonal↗
PubMedDate not supplied

Hypothesis: systemic lupus erythematosus as a disease secondary to polyclonal lymphocyte activation.

Systemic lupus erythematosus (SLE) is characterized by the concomitance of B cell polyclonal activation and the production of a wide spectrum of autoantibodies showing a marked preference for nuclear antigens. We propose the hypothesis that the production of the most pathogenic antinuclear antibodies with high affinity and IgG isotype is driven by antigens liberated by the death of rapidly proliferating lymphoid cells. The disease could evolve in three steps: (1) polyclonal B cell activation and proliferation caused by unknown etiologic factors (virus?, mitogen? ...); (2) primary activation of natural antibody-producing clones leading to the appearance in the serum of large amounts of natural autoantibodies with public idiotype; and (3) secondary immunization against molecules synthesized in large quantities during lymphocyte proliferation, released by dying cells and subsequently presented in an immunogenic form to T cells. These molecules include nucleic acids (DNA, RNA), nucleic acid-binding proteins (histones, Ro, La), and parts of the RNA splicing machinery (RNP). Other autoantibody activities could relate to cross-reactivities or the binding properties of DNA-anti-DNA immune complexes.

Animals↗
PubMedDate not supplied

[Glomerulonephritis].

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Glomerulonephritis↗
PubMedDate not supplied

[Circulating immuns complexes and infections endocarditis. 64 cases (author's transl)].

An immunological study, with examination for circulating immune complexes (CIC) by precipitation by polyethylene-glycol (PEG) and by fixation of labelled C1q, was carried out in 64 patients with infectious endocarditis (IE). One or more complementary studies during the course of the illness were possible in 23. CIC were found in 84 p. 100 of cases (66 p. 100 of acute IE and 89 p. 100 of subacute IE), during the active phase of the disease. High levels of PEG precipitate were correlated with typical cutaneous signs (including Osler's nodes), with the presence of cryoglobulins. With effective antibiotic treatment, the level of PEG precipitate (17 patients) returned to normal within one month, in parallel with a fall in rheumatoid factor and in cryoglobulins. By contrast, ineffective treatment was invariably reflected (6 patients) by a rise in levels of PEG precipitate. The estimation of CIC using the PEG technique during IE would already appear to be a value aid in cases of difficult diagnosis, and a research area worthy of further exploration within the context of IE.

Adolescent↗
PubMedDate not supplied

The multifactorial etiology of autoimmune diseases.

The etiology of autoimmune diseases remains a matter of debate. The respective roles of predisposition genes and environmental factors on the one hand, and the opposing effect of promoting and protective factors, on the other hand, are still ill-defined. A large amount of data recently obtained in either experimental models or in human diseases open new perspectives in the understanding of this etiology. We shall briefly review here some of these data.

Animals↗
PubMedDate not supplied

In vivo T cell activation properties of anti-T cell monoclonal antibodies.

Murine monoclonal antibodies specifically directed at the CD3 molecular complex are widely used in clinical transplantation. They are potent inhibitors of immune function and may be administered in association with conventional immunosuppressive drugs. However, their use has been complicated by the severe clinical syndrome that invariably follows the first injections of the antibody. We have shown that this reaction relates to transient T cell activation, with production of a cohort cytokines. This in vivo activating effect is unique to anti-CD3 MoAbs. Furthermore, this property is highly monocyte-dependent, engaging Fc receptors, and thus varies according to the isotype of the administered MoAb. Another anti-T cell MoAb such as the BMA031 directed towards monomorphic determinants of the T cell receptor (TCR) does not promote such massive in vivo activation.

Animals↗
PubMedDate not supplied

Properties of bispecific rosette-forming cells. III.---Antigen binding cells with double specificity after immunization with two covalently linked antigens.

Adult C57B1/6 mice were immunized with bovine serumalbumin and horse radish peroxidase administered simultaneously but either separated or covalently linked by glutaraldehyde treatment. The percentage of double rosettes formed with both antigens (coupled to red cells) as compared to the total rosette forming cells reached 20% when mice had been injected by the conjugate whereas it remained less than 2% in case of separate antigen administrations. In addition, these bispecific rosettes were inhibited after anti-theta serum plus complement treatment.

Animals↗