267 research outputs found

    T cell studies in a peptide-induced model of systemic lupus erythematosus

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    We have previously reported that immunization with a peptide mimetope of dsDNA on a branched polylysine backbone (DWEYSVWLSN-MAP) induces a systemic lupus erythematosus-like syndrome in the nonautoimmune BALB/c mouse strain. To understand the mechanism underlying this breakdown in self tolerance, we examined the role of T cells in the response. Our results show that the anti-foreign and anti-self response induced by immunization is T cell dependent and is mediated by I-Ed-restricted CD4+ T cells of the Th1 subset. In addition, generation of the critical T cell epitope requires processing by APCs and depends on the presence of both DWEYSVWLSN and the MAP backbone. The breakdown in self tolerance does not occur through cross-reactivity between the T cell epitope of DWEYSVWLSN-MAP and epitopes derived from nuclear Ags. In this induced-model of SLE, therefore, autoreactivity results from the activation of T cells specific for foreign Ag and of cross-reactive anti-foreign, anti-self B cells. Despite the fact that tissue injury is mediated by Ab, the critical initiating T cell response is Th1

    Isolation of Rabbit Lymphocytes and Serological Study of Their Alloantigens

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    For the past 3 years NZB and NZW mice have been maintained by sister-brother matings from English breeder stock. NZB/NZW F1 hybrids developed lupus-like nephritis during the 6th to 7th month and few survived beyond the 8th month. Renal tissues of these animals were examined with fluorescein-labeled antinucleoside sera, specific for thymine and cytosine, for the presence of denatured DNA in GCW, and with labeled antibody to mouse IgG for the presence of excess host globulin in the same areas. The following results have been obtained: (a) All 51 hybrids, over 5 months of age, had an excess of mouse globulin in GCW. 40 animals between the ages of 5 and 12 months showed, in the same areas, antigens which bound one or both of the antinucleoside antibodies. (b) Renal tissues of 19 NZB mice, 5–19 months old, and 27 NZW mice, 2–18 months old, were examined. Excess host globulin was seen in GCW of 13 NZB and 20 NZW animals. The tissues of only two old NZB mice, 14 months of age, bound antinucleoside antibody but none of the other animals did. The association of rapidly fatal lupus-like nephritis in NZB/NZW F1 mice with denatured DNA and mouse globulin in GCW supports the hypothesis involving this antigen-antibody complex in the pathogenesis of the disease


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    Serum monoclonal macroglobulins were detected in over 30% of NZB/NZW F1 mice greater than 11 mo of age. The monoclonal nature of the IgM was shown by restricted electrophoretic mobility, characteristic appearance on immunoelectrophoresis, restriction to a single light chain type, and ability to induce anti-idiotypic antisera. The monoclonal macroglobulins were separated from antibodies to DNA and RNA that migrated in the 7S region of sucrose gradients. Enlarged lymph nodes were often present in mice with monoclonal IgM, and a transplantable IgM-producing lymphoid tumor was established from the spleen of one animal

    Expression of aberrant forms of CD22 on B lymphocytes in Cd22a lupus-prone mice affects ligand binding

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    CD22 functions primarily as a negative regulator of B-cell receptor signaling. The Cd22a allele has been proposed as a candidate allele for murine systemic lupus erythematosus. In this study, we explored the possible expression of aberrant forms of CD22, which differ in the N-terminal sequences constituting the ligand-binding site due to synthesis of abnormally processed Cd22 mRNA, in several Cd22a mouse strains, including C57BL/6 Cd22 congenic mice. The staining pattern of splenic B cells obtained with CY34 anti-CD22 mAb, which was expected to bind poorly to the aberrant CD22, was more heterogeneous in Cd22a mice than in Cd22b mice. Moreover, CD22 detected on B cells of Cd22a mice was expressed more weakly and as a smaller-sized protein, compared with Cd22b mice. Significantly, analysis with a synthetic CD22 ligand demonstrated that Cd22a mice carried a larger proportion of CD22 that was not bound by cis ligands on the B-cell surface than Cd22b mice. Finally, the study of C57BL/6 Cd22 congenic mice revealed that Cd22a B cells displayed a phenotype reminiscent of constitutively activated B cells (reduced surface IgM expression and augmented MHC class II expression), as reported for B cells expressing a mutant CD22 lacking the ligand-binding domain. Our demonstration that Cd22a B cells express aberrant forms of CD22, which can potentially deregulate B-cell signaling because of their decreased ligand-binding capacity, provides further support for Cd22a as a potential candidate allele for murine systemic lupus erythematosu
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