B cell lymphokines in human systemic lupus erythematosus.

B lymphocytes of patients with systemic lupus erythematosus were studied to determine if they were intrinsically hyperresponsive to lymphokine mediators. Peripheral blood B cells from 25 lupus patients and 16 normal individuals matched for age and sex were cultured with recombinant lymphokines. B cells both from patients and normal subjects did not show increased [3H]thymidine uptake when cultured with interleukins 1, 2, and 4. The addition of Staphylococcus aureus Cowan I as costimulant increased [3H]thymidine uptake by B cells of patients and normal subjects. In the absence of T cells these recombinant lymphokines did not increase in vitro IgG or IgM production by lupus or normal B cells. Other recombinant lymphokines, interleukin 3, interferon gamma, lymphotoxin, tumour necrosis factor, and colony stimulating factors for granulocytes and macrophages were tested on lymphocytes from smaller numbers of patients and controls. Most patients in this study had inactive disease and all data suggested that B cells from patients with inactive lupus were not hyperresponsive to the lymphokines tested. In addition, the use of lymphokine gene probes for interleukins 2, 3, and 4 did not show spontaneous expression of these genes in circulating lymphocytes.