Clinical immunology and immunopathology最新文献

d-penicillamine (d-PA) was reported to induce various immunological abnormalities including production of autoantibodies to insulin. These abnormalities were mainly described in patients with primary immunological disorders such as rheumatoid arthritis. In order to clarify whetherd-PA-induced immune disorders are restricted to patients genetically prone to develop autoimmune diseases or to a direct drug effect, we tested for the presence of various autoantibodies and for molecular HLA typing in 17 patients with Wilson's disease treated with this drug. In 2/17 patients, low-titer (10 JDFU) circulating islet cell autoantibodies (ICA) were detected, while another patient was positive for the presence of insulin autoantibodies. None of the sera tested showed reactivity for glutamic acid decarboxylase or ICA512. Five of twelve patients were positive for anti-single-stranded DNA autoantibody. Molecular HLA typing of the autoantibody-positive subjects showed that they carry HLA haplotypes not associated with insulin-dependent diabetes. The insulin response to intravenous glucose tolerance test in two patients with autoantibodies was found to be normal. A second blood testing of the autoantibody-positive patients 5 months following initial evaluation revealed conversion to negativity in all three. Our results suggest thatd-PA-induced autoantibodies in patients with Wilson's disease are independent of the immunogenetic background characteristics of diabetes.

Secondary immune responses to T-independent antigens are characterized by little or no affinity maturation, a phenomenon attributed to limited somatic hypermutation. In the human immune response toHaemophilus influenzaetype b capsular polysaccharide, however, there are numerous differences between rearranged heavy chain variable region gene segments and candidate germline genes, irrespective of antigen presentation in a T-independent or T-dependent form. To determine the characteristics of somatic hypermutation in this response, we analyzed rearranged heavy chain variable region segments and associated 3′ untranslated JH4–JH5 introns from monoclonal anti-Hib PS antibodies. Mutation of untranslated introns and heavy chain variable segments in both T-independent and T-dependent responses resembles that described in murine and unselected human immune responses. Although mutation is frequent in both T-independent and T-dependent anti-Hib PS responses, there is little evidence of antigen-driven selection, suggesting that ongoing pressure to conserve the variable segment germline configuration limits affinity maturation in this immune response.

Murine graft-versus-host (GVH) disease takes two forms depending upon the parental/F1 strain combination employed. Anemia, lymphopenia, hypogammaglobulinemia, profound anti-F1 cytotoxicity, and the loss of cytotoxic potential against third party alloantigen is seen in acute lethal GVH disease. In contrast to this, in chronic GVH disease there is polyclonal B cell activation, auto-antibody production, no anti-F1 cytotoxicity, and retained cytotoxicity against allotargets. We have previously reported that this marked disparity in disease expression results from a radiosensitive host veto cell which protects the F1 mouse from parental anti-F1 cytotoxicity in mice undergoing CGVH disease. This cell could be inducedin vitroorin vivoin CGVH disease. Using anin vitrosystem, we now demonstrate that a CD4⁺, radiation-sensitive, T cell does emerge in acute lethal GVH disease which is capable of down-regulating cytotoxicity. The cell does not appear to be a veto cell in that it attenuates cytotoxicity directed against nonself alloantigen. The function of this cell does not appear to be influenced by minor lymphocyte stimulatory gene products. We further report that, in ALGVH disease, regulation by this cell is not readily apparent due to the emergence of a CD8⁺T cell of parental (B6) origin, which opposes its action.

Recently, we presented evidence that lipopolysaccharide (LPS) treatment of BALB/c mice induces an enhancement on mononuclear phagocytic system functions, leading to a more efficient clearance of immune complexes (IC). In the present study we analyzed the role of tumor necrosis factor alpha (TNF-α), one of the earliest mediators released after LPS injection, in the clearance of IC. Our results show that the enhancing effect of LPS on clearance can be partially reproduced by intravenous injection of sera from mice injected with LPS 1 h before. At this time point, the levels of TNF-α reach a maximal peak of 240 ± 73 U_50%/ml [TNF-α (+) serum]. However, sera obtained after 4 h of LPS injection, with a TNF-α activity of 3.5 U_50%/ml [TNF-α (−) serum], did not exert any relevant effect on IC clearance. In addition, the effect of TNF-α (+) serum was completely blocked by preincubation with rabbit anti-TNF-α antibody. Moreover, the enhancement of IC clearance can be similarly induced by administering murine recombinant TNF-α. Furthermore, the LPS-insensitive C3H/HeJ mice, which do not secrete TNF-α in response to LPS, showed a normal IC clearance after LPS injection. Taken together, these results strongly suggest that the enhancement of IC clearance by LPS treatment could be mediated, at least in part, by TNF-α.

Tolerance to experimental autoimmune myasthenia gravis by nasal administration of microgram amounts of acetylcholine receptor (AChR) has been reported. To elucidate the mechanisms behind tolerance induction via the respiratory tract and the involvement of CD4⁺T cells, we established AChR-specific CD4⁺CD8⁻T cell clones from nasally tolerized rats. Nasal tolerance decreased leukocyte function-associated antigen-1 (LFA-1) expression in CD4⁺T cells from tolerized rats. There was no difference between nasally tolerized and control rats in expression of intercellular adhesion molecule-1. The levels of transforming growth factor-β (TGF-β) mRNA-expressing cells were upregulated in CD4⁺T cell clones after tolerance induction. These findings suggest that decreased LFA-1 expression in CD4⁺T cells contributes to reduction of the infiltration of inflammatory CD4⁺T cells, while upregulated TGF-β may inhibit lymphocyte functions.

The shifting balance between proteinases and proteinase inhibitors in blood, a function of their relative affinities and concentrations, has long been hypothesized to influence immune competency. The identification of proteinase-activated receptor responses in cells of the mononuclear phagocyte system suggests a potential explanation. The major serum proteinase inhibitor, α₁proteinase inhibitor (α₁PI, α₁-antitrypsin), has been reported to increase in concentration during inflammation. Quantitative determination of serum α₁PI has traditionally been performed nephelometrically; however, antigenically quantitated levels may not be representative of functional capacity. It has previously been observed that α₁PI in serum exhibits bimodal behavior as the result of various concentrations of proteinase inhibitors, specifically α₂macroglobulin (α₂M) and inter-α-trypsin inhibitor, which compete in binding to a panel of serine proteinases. Consequently, it has not previously been possible to assign a numerical value for the specific activity of these competing proteinase inhibitors in serum. By applying known constants representing the association of proteinase inhibitors with porcine pancreatic elastase (PPE), the theoretical relationship between the functional and antigenic values for α₁PI and α₂M has been empirically derived allowing, for the first time, the calculation of their specific activities in serum. As predicted, the serum concentration of α₁PI was found to be highly correlated with residual uninhibited PPE catalytic activity in healthy individuals, but not in individuals exhibiting fragmented or complexed α₁PI. Using these techniques, both the antigenic and functional levels of α₁PI were determined in sera from subjects with insulin-dependent diabetes mellitus (IDDM) who had been clinically diagnosed as having either periodontal disease or gingival health. Determination of quantitative levels by antigen-capture suggests that the IDDM subjects with periodontitis manifest dramatically increased levels of fragmented serum α₁PI compared with their orally healthy counterparts or normal controls. In contrast, functional analysis of serum α₁PI revealed no differences between the three subject populations. The elevated levels of antigenically determined serum α₁PI reflect the inflammatory status of periodontal disease. These results support the importance of and provide methodology for determining the functionally active levels of α₁PI allowing reexamination of changes detected during the acute phase of inflammation, replacement therapy, and longitudinal studies in relevant disease processes including malignancy and diabetes.