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 the presence of high titers of autoantibodies against uridine-rich RNA-small nuclear ribonucleoprotein (snRNP) Ag. Because the presence of such snRNP-reactive autoantibodies has recently been shown to be associated with polymorphisms of HLA, this study was undertaken to determine whether snRNP-reactive T cells could be identified and characterized from 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 two healthy blood donors who possessed disease-associated HLA genotypes. The cell surface phenotype of clones determined by flow cytometry was CD3+, CD4+, CD45RO+, TCR V alpha beta+. TCR V beta analysis, performed using V beta-specific primers and polymerase chain reaction, revealed that the T cell lines generated were clonal; a limited number of TCR V beta genes were expressed among the clones tested. All clones tested by mAb blocking of Ag-induced proliferation were restricted by HLA-DR. Several T cell clones were identified that were specific for B'/B or D polypeptides. These results demonstrate that snRNP-reactive T cells can be isolated from SLE and MCTD patients in vitro, and that Ag-driven expansion of such T cells could play a role in the immunopathogenesis of these diseases in vivo.