ANTI-RIBOSOMAL AND P-PEPTIDE-SPECIFIC AUTOANTIBODIES BIND TO T-LYMPHOCYTES

Patients with systemic lupus erythematosus (SLE) frequently have anti- lymphocyte autoantibodies, some of which also bind to surfaces of neur ons. Since anti-ribosomal P protein autoantibodies (anti-P) from SLE p atients also bind to surfaces of neurons, we hypothesized that anti-P are anti-lymphocyte antibodies. A panel of human T lymphocytes was eva luated for anti-P binding by indirect immunofluorescence. Affinity-pur ified anti-ribosomal antibodies were used as a source of anti-P. These autoantibodies bound to the surfaces of all transformed T cell lines tested. This binding was not mediated by Fc receptors. It was inhibita ble by ribosomes. Anti-P bound to circulating T lymphocytes from healt hy adults and children. They also bound to thymocytes and cord blood T cells from normal neonates. Circulating T cells from SLE patients wit h anti-P bound less anti-P than cells from healthy controls. Two patie nts were studied on multiple occasions. The capacity of their T cells to bind anti-P correlated inversely with titres of anti-ribosomal anti bodies. Anti-ribosomal antibodies, other than anti-P, also appear to b ind to T cells. The surface of T cells contains a protein with the siz e and antigenicity of the ribosomal P protein, P0. We conclude that an ti-ribosomal antibodies are a subset of anti-lymphocyte autoantibodies . Their possible role in the pathogenesis of lymphopenia or lymphocyte dysfunction in SLE has to be defined in further studies.