Correlation of T and B cell activities in vitro and serum IL-2 levels in systemic lupus erythematosus.
There have been only a few studies indicating that B cell hyperactivity in SLE could depend on Th cell activation. In particular, circulating CD4+ cells were found to express Ia. Our own previous investigations have shown that the decreased IL-2 secretion capacity in vitro of CD4+ cells in SLE is restored to normal when the cells are rested for a few days in culture. This suggested the presence of activated, exhausted T cells in the circulation. In this study, we report several observations concerning T cell function in SLE. 1) Decreased IL-2 secretion in vitro of PBL was found to correlate significantly with increased spontaneous IgG secretion of such cells; immunosuppressive treatment of 22 patients with steroids plus cyclosporin A led, to a large extent, to a correction of both abnormalities. 2) 9 of 18 patients with active disease (and low IL-2 secretion in vitro) had increased IL-2 levels in serum by ELISA; two sera contained IL-2 biologic activity, and chromatography of one serum showed IL-2 in a high molecular size complex (Mr approximately 50,000) dissociable with 6 M urea. The serum levels of IL-2R were also frequently increased, even in less active SLE. 3) In cell culture experiments, the IgG secretion by purified B cells from 6 of 9 patients with active SLE was increased by autologous T cells acting either alone (3 patients) or synergistically with rIL-2 (3 patients); the B cells from all 9 patients showed increased IL-2 responsiveness compared with blood donor B cells. Taken together, these results provide new evidence that increased T cell activation occurs and plays a role in SLE.
D000328:Adult; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000097:blood* / Q000378:metabolism; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000188:drug therapy / Q000276:immunology; D008222:Lymphokines / Q000097:blood; D008297:Male; D008970:Molecular Weight; D011971:Receptors, Immunologic / Q000032:analysis; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*
D007074:Immunoglobulin G; D007376:Interleukin-2; D008222:Lymphokines; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; C046147:interleukin 2 inhibitor