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[Antilymphocytic humoral autoimmune response of mice with developing Rauscher leukemia directed against group-specific retrovirus antigens].

The methods of indirect membrane immunofluorescence, immunoenzyme analysis, complement-dependent cytotoxicity and sorption tests were used to demonstrate two types of humoral antilymphocytic autoimmune reactions at the early stage of the Rauscher leukemia in mice of BALB/c, BDF1 and C57B1/6 strains. The first one is directed against group-specific oncoviral antigens (p30, p15) expressed on the lymphocyte membrane of both intact mice and of those with leukemia, the second one is virus-independent and possesses strain specificity.

Animals↗

Alcohol dehydrogenase: a target of humoral autoimmune response in liver disease.

BACKGROUND & AIMS: Liver-specific membrane lipoprotein (LSP) is a heterogeneous liver preparation that has been widely used to study autoreactivity in liver disease. The aim of this study was to identify autoantigens in LSP. METHODS: Guinea pig anti-LSP serum was used to screen a human liver complementary DNA (cDNA) library. Humoral immune responses to isolated potential autoantigens were investigated by immunoblotting in 91 pediatric patients with various liver diseases, 20 adult patients with alcoholic liver disease and 20 with autoimmune thyroid disease, 37 healthy children, and 20 healthy adults. RESULTS: A 1.6-kilobase cDNA insert isolated from the cDNA library was found to encode amino acids 61-374 of the human alcohol dehydrogenase (ADH)-gamma 1 subunit. Antibodies to this or other ADH subunits were found significantly more frequently in autoimmune liver diseases (19 of 39 patients; 49%), Wilson's disease (5 of 13 patients; 38%), and alcoholic liver disease (10 of 20 patients; 50%) than in normal controls (P < 0.0001, P < 0.005, and P < 0.05, respectively) and correlated with disease activity in autoimmune liver disease. CONCLUSIONS: ADH has been identified as a new antigenic component of the LSP using a xenogeneic antiserum to immunoprobe a human cDNA liver library and seems to be a target autoantigen in liver disease. This approach may be useful in identifying other potential autoantigens.

Adolescent↗

B-1 cells in systemic autoimmune responses: IgM+, Fc epsilon Rdull B cells are lost during chronic graft-versus-host disease but not in murine AIDS or collagen-induced arthritis.

The potential role of B-1 cells (i.e. the CD5+ B cell and "sister" B cell subsets) in autoimmunity is controversial. CD5+ B cells have been shown to secrete antibodies of similar specificity as those found in many systemic autoimmune diseases; in addition, increases in CD5+ B cell frequency have been reported in patients suffering from rheumatoid arthritis, Sjögren's syndrome, myasthenia gravis, insulin-dependent diabetes mellitus and Hashimoto's thyroiditis. Whether these increases are due to expansion of B-1 lineage cells in the human or due to activation-induced expression of CD5 by conventional B cells is unclear. In the present study, we used three murine models of systemic autoimmunity: murine acquired immunodeficiency syndrome (MAIDS), chronic graft-versus-host disease (cGvHD), and collagen-induced arthritis (CIA) to determine whether increases in B-1 cell frequency are universally seen in models of autoimmunity which are mechanistically distinct. In contrast to the aforementioned human systemic autoimmune diseases which exhibit an increase in CD5+ B cell frequency, the percentage of CD5+ B cells declined in all three murine models of systemic autoimmune disease. Even though there was a decrease in the frequency of CD5+ B cells there was no change in the actual number of CD5+ B cells. Thus, the apparent decline in CD5+ B cell frequency was due to increases in either T cells, conventional Fc epsilon R+ B cells, or both. The only actual decline in a B cell subset was the loss of IgM+, Fc epsilon Rdull cells in both the spleen and peritoneal cavity of mice undergoing a chronic graft-versus-host reaction. Therefore, our data suggests that expansion of the B-1 subset does not occur as a general feature of murine systemic autoimmune disease. These observations, consistent with previous studies of Ig gene usage in autoreactive antibodies, support the view that expansion and differentiation of the CD5+ B cell subset is not a central event leading to autoantibody production.

Animals↗

Autoimmune response of patients with paraneoplastic cerebellar degeneration to a Purkinje cell cytoplasmic protein antigen.

Sera from 6 of 12 patients with paraneoplastic cerebellar degeneration (PCD) contained anti-Purkinje cell antibodies, as determined by indirect immunofluorescence on frozen sections of normal human cerebellum. Samples of cerebrospinal fluid from 2 of the patients with serum antibodies were tested, and both specimens contained anti-Purkinje cell antibody. The anti-Purkinje cell antibodies were polyclonal, fixed complement, and were present in all patients at serum dilutions of 1:1,000 or greater. Antibody activity could not be suppressed by preabsorption of sera with human or animal brain and tissue powders or with fresh crude human cerebellar extracts. No anti-Purkinje cell antibodies were detected in control sera from 167 neurologically normal cancer patients, 32 normal volunteers, 10 patients with other causes of cerebellar degeneration, or 8 patients with other paraneoplastic neurological diseases. Preliminary evidence suggests that the Purkinje antigen is a protein that is often concentrated in the periphery of the cytoplasm in disc-shaped structures. Patients with antibodies often developed signs of PCD near the time of detection of the tumor and had relentless progression of neurological disease. Patients without antibodies frequently had cancer for months to years before PCD developed, and often had spontaneous stabilization of neurological disease with time. Four patients without and 3 patients with antibodies underwent plasmapheresis without response.

Aged↗

Humoral autoimmune responses to glutamic acid decarboxylase have similar target epitopes and subclass that show titer-dependent disease association.

Glutamic acid decarboxylase (GAD) is an autoantigen in stiff man syndrome (SMS) and type 1 diabetes (T1DM). Different GAD autoantibody characteristics in these disorders have suggested distinct underlying mechanisms of autoimmunity. Here, it is shown that increased prevalence of autoantibodies to GAD65 amino terminal and GAD67 epitopes and autoantibodies of IgG2, IgG3, or IgG4 subclass in patients with SMS (P < 0.001 vs. T1DM) are secondary to the markedly higher autoantibody titers in SMS patients (P < 0.0001) and that autoantibody epitopes and subclasses were similar when patients were matched for autoantibody titer. Exposure to autoantigen in the disorders is likely to involve similar humoral antigenic determinants, but different B cell regulation.

Antibody Formation↗

Induction of an autoimmune response against syngeneic lymphoma cells by immunogenic 64-kDa protein isolated from normal blast cells of BALB/c mice.

Immunogenic proteins with identical molecular mass (64 kDa) were purified from a syngeneic spontaneous T cell leukaemia line, designated LB3, and lymphoblast extracts both derived from BALB/c mice. The 64-kDa protein was purified by a sequence of biochemical steps from cell extracts containing protease inhibitors. The following steps were included in the purification pathway: Sephadex G-100 gel filtration, anion-exchange chromatography, concanavalin A (ConA) affinity chromatography, and preparative gel electrophoresis. The immunogenic fraction isolated in each step was subjected to the next step along the purification pathway. The immunogenicity of the separated fractions was measured by a lymph-node proliferation assay, which is indicative of delayed-type hypersensitivity. The final 64-kDa isolated protein of blast cells induced in BALB/c mice an efficient lymph-node proliferation response, which was detected in the regional lymph node after challenge with the final isolated protein of LB3 cells and vice versa. In addition to their identical molecular mass, both proteins were eluted from an anion-exchange column with the same NaCl concentration (0.57 M) and both expressed affinity to the ConA-Sepharose column, suggesting that they are glycosylated. The specificity of the immunological responses induced or elicited with the various isolated proteins was also shown. The implications of these findings are discussed.

Animals↗

Regulation of PD-1, PD-L1, and PD-L2 expression during normal and autoimmune responses.

Newer members of the B7-CD28 superfamily include the receptor PD-1 and its two ligands, PD-L1 and PD-L2. Here, we characterize the expression of PD-1, PD-L1, and PD-L2 in tissues of naive miceand in target organs from two models of autoimmunity, the pancreas from non-obese diabetic (NOD) mice and brain from mice with experimental autoimmune encephalomyelitis (EAE). In naive mice, proteiexpression of PD-1, PD-L1, and PD-L2 was detected in the thymus, while PD-1 and PD-L1 were detected in the spleen. PD-L1, but not PD-L2, was also detected at low levels on cardiac endothelium, pancreatic islets, and syncyciotrophoblasts in the placenta. In pre-diabetic NOD mice, PD-1 and PD-L1 were expressed on infiltrating cells in the pancreatic islets. Furthermore, PD-L1 was markedly up-regulated on islet cells. In brains from mice with EAE, PD-1, PD-L1, and PD-L2 were expressed on infiltrating inflammatory cells, and PD-L1 was up-regulated on endothelium within EAE brain. The distinct expression patterns of PD-L1 and PD-L2 led us to compare their transcriptional regulation in STAT4(-/-), STAT6(-/-), or NF-kappaB p50(-/-)p65(+/-) dendritic cells (DC).PD-L2, but not PD-L1, expression was dramatically reduced in p50(-/-)p65(+/-) DC. Thus, PD-L1 and PD-L2 exhibit distinct expression patterns and are differentially regulated on the transcriptional level.

Animals↗

IgG1 subclass dominates autoimmune response to tyrosine phosphatase-like molecule IA-2 in Chinese type 1 diabetes patients.

BACKGROUND AND AIMS: Islet autoantibodies are known markers for type 1 diabetes with an immune-mediated basis; their isotype or subclass profiles may also provide clues to changes in immune response during disease or after intervention. For ICAs and GADab, the IgG1 subclass consistently dominates in recent-onset disease. The aims of our study were to determine the isotype patterns for IA-2ab in Asian Chinese patients with autoimmune diabetes. MATERIALS AND METHODS: From an initial screening of over 400 diabetes patients, 40 subjects (mean age 22.2 +/- 15.8 years) with IA-2ab were enrolled for this study. IA-2ab was detected by radioimmunoassay of [35S]-labelled recombinant human IA-2 ic(605 - 979). Of them, 31 (median age 15 years, range 2 - 57 years; 16 children) had clinical type 1 diabetes (that is, they required insulin at onset or within 1 year) with the majority having been recently diagnosed (< 1 year). The other 9 patients had clinical type 2 diabetes phenotype. RESULTS: IA-2ab IgG subclasses determined with monospecific secondary antibodies showed that both type 1 diabetic adults and children had similarly non-restricted isotype patterns with a strong presence of IgG1-IA-2ab. The rank order was IgG1 > 3 > 2 > 4; 15 subjects had detectable IgG4-IA-2ab. Clonality of immune response determined with kappa/lambda chain-specific antibodies also showed a non-restricted pattern. Patients aged 38.2 +/- 15.2 years with type 2 diabetes had broad patterns of isotypes - IgG1/3 was detected more frequently (n = 8) than IgG2/4 (n = 5). Of three patients on insulin treatment, one was also positive for GADab. The remaining 6 patients were on oral hypoglycaemic treatment. IA-2ab in type 2 diabetes showed a low titre compared to type 1 diabetes. CONCLUSIONS: Isotype responses to IA-2 had a strong IgG1 presence, similar to ICAs and GADab. With IgG3 subclass representation, a predominant Th1 milieu in the systemic environment is likely. There is no suggestion of differences in immune response to IA-2 between adults and children with type 1 diabetes.

Adolescent↗

Contribution of alphabeta and gammadelta T cells to the generation of primary immunoglobulin G-driven autoimmune response in immunoglobulin- mu-deficient/lpr mice.

Class switch recombination (CSR) is a T-cell-dependent mechanism regulating isotype switching in activated mature B cells. Recently we showed that T-cell-independent CSRs occur spontaneously during B lymphopoiesis, but such cells are negatively selected by Fas signalling. In immunoglobulin mu-deficient mice, lack of Fas rescues isotype-switched B cells, resulting in generation of an autoimmune primary immunoglobulin G (IgG) repertoire in muMT/lpr mice. In the present study, we studied the role of alphabeta and gammadelta T cells in regulating this primary gammaH-driven repertoire. We found that a lack of alphabeta T cells significantly inhibited IgG production and autoimmunity in muMT/lpr mice, whereas a lack of gammadelta T cells resulted in augmented IgG production and autoimmunity. Also, a lack of T cells in muMT mice rescued isotype-switched B cells and serum IgG, probably owing to the lack of available FasL. We suggest that although CSRs in B-cell lymphopoiesis are T-cell independent, alphabeta T cells are important in the expansion of isotype-switched B-cell precursors and in promoting gammaH-driven autoimmunity, whereas gammadelta T cells regulate these cells.

Animals↗