Autoreactive human T cell lines recognizing ribosomal protein L7

Sera of patients suffering from systemic lupus erythematosus (SLE) frequent ly contain oligoclonal IgG autoantibodies with high affinity for the riboso mal protein L7 (rpL7), The humoral autoimmune response to rpL7 apparently i s driven by antigen and T cell dependent. In order to analyze the T cell re sponse to rpL7 we cultured peripheral blood lymphocytes of healthy individu als and SLE patients in the presence of recombinant rpL7, After 10 days, th e cytokine response to restimulation with rpL7 was examined using a spot-EL ISA. Measuring IFN-gamma secretion, the T cells of two patients and four he althy donors showed a significant increase in the number of spots as compar ed to control cells. Secretion of IL-4 or IL-10 was not detected. From the antigen-stimulated primary cultures we established by limiting dilution clo ning six rpL7-reactive, IFN-gamma-secreting T cell lines which show a CD3()CD4(+)CD8(-) phenotype, One line additionally was shown to be positive for HLA-DR and CD45R0, but negative for CD27 and CD31. The cell lines carry al pha beta TCR chains which differ from each other in sequence and specificit y. rpL7 fragments rich in basic amino acids could be identified as epitopes recognized by the TCR of three cell lines. Recognition of rpL7 is HLA-DRG restricted or respectively HLA-DP restricted in the two cell lines analyzed .