Reactivity of RA and SLE lymphocytes stimulated by anti-Ig antibodies.

human lymphocyte stimulation response was studied using phytohaemagglutinin and immunoabsorbent-column purified rabbit antibodies to γA, γM and γG with peripheral blood lymphocytes from normal subjects as well as patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). In addition, lymphocytes from a group of patients receiving immunosuppressive therapy in connection with renal transplantation or metastatic carcinoma were studied as controls. No essential differences in degree of response were noted when normal subjects were compared to RA patients, however, most SLE patients showed a decreased response with the various purified anti-Ig antibodies. This hyporesponsiveness was most marked using anti-IgM and anti-IgG antibody (<0·01). Patients receiving immunosuppressive drugs for maintenance of renal transplants or in the course of treatment for metastatic carcinoma also showed significant depression of responses in lymphocyte culture (<0·01) after stimulation with anti-IgG, IgA, or IgM antibody. In addition, baseline unstimulated cellular incorporation of labelled thymidine, as well as degree of stimulation with phytohaemagglutinin, was significantly reduced (<0·01) among the immunosuppressed control group when compared to normals or the groups of SLE or RA patients. Diminished culture response in SLE patients and subjects receiving immunosuppressive therapy may be related to concurrent therapy or to other alterations intrinsic to the disease process itself.