HUMAN T-CELL CLONES REACTIVE AGAINST U-SMALL NUCLEAR RIBONUCLEOPROTEIN AUTOANTIGENS FROM CONNECTIVE-TISSUE DISEASE PATIENTS AND HEALTHY-INDIVIDUALS

SLE and mixed connective tissue disease (MCTD) are characterized by th e presence of high titers of autoantibodies against uridine-rich RNA-s mall nuclear ribonucleoprotein (snRNP) Ag. Because the presence of suc h snRNP-reactive autoantihodies has recently been shown to be associat ed with polymorphisms of HLA, this study was undertaken to determine w hether snRNP-reactive T cells could be identified and characterized fr om patients. PBMC were stimulated with affinity-purified snRNP Ag and cloned by limiting dilution in the presence of rIL-2 and rIL-4. snRNP- reactive human T cell clones were generated from three patients and tw o healthy blood donors who possessed disease-associated HLA genotypes. The cell surface phenotype of clones determined by flow cytometry was CD3+, CD4+, CD45RO+, TCR Valphabeta+. TCR Vbeta analysis, performed u sing Vbeta-specific primers and polymerase chain reaction, revealed th at the T cell lines generated were clonal; a limited number of TCR Vbe ta genes were expressed among the clones tested. All clones tested by mAb blocking of Ag-induced proliferation were restricted by HLA-DR. Se veral T cell clones were identified that were specific for B'/B or D p olypeptides. These results demonstrate that snRNP-reactive T cells can be isolated from SLE and MCTD patients in vitro, and that Ag-driven e xpansion of such T cells could play a role in the immunopathogenesis o f these diseases in vivo.