A NONCYTOTOXIC SUPPRESSOR OF IMMUNOGLOBULIN-SYNTHESIS AND SECRETION BY B-CELLS OF NORMAL HUMANS AND PATIENTS WITH RHEUMATOID-ARTHRITIS AND SYSTEMIC LUPUS-ERYTHEMATOSUS

A factor secrected by thymocytes of immunized rabbits totally suppressed both the initiation of, and ongoing synthesis and secretion of, lectin (PWM)-induced synthesis of IgM and IgG immunoglobulins by the circulating B lymphocytes of normal humans, and of twenty consecutive patients with rheumatoid arthritis and twelve consecutive patients with systemic lupus erythematosus. The suppressor factor, referred to as human Ig synthesis/secretion suppressor factor or HISSF, is not HLA restricted in its activity and is not cytotoxic to the circulating human mononuclear cells (B cells, T cells. Null cells and monocytes). It was demonstrated that T cells precultured with HISSF were transformed into suppressor cells which, when added to fresh cultures of autologous B cells, suppressed the synthesis and secretion of IgM and IgG. On the basis of its suppressive and non-cytotoxic properties in vitro, HISSF may be an effective immunosuppressant in the treatment of patients with autoimmune diseases. © 1991 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.