Mitogenic Responses to Lipopolysaccharide by B Lymphocytes from Patients with Systemic Lupus Erythematosus

Peripheral blood lymphocytes from 43 patients with systemic lupus erythcmatosus (SLE) and from age‐ and sex‐matched normal controls were cultured with lipopolysaccharide (LPS) to examine the response to the polyclonal B‐cell activator. Lymphocytes from active SLE patients incorporated 4840±471 (mean ± SE) cpm in response to LPS, whereas lymphocytes from inactive SLE patients incorporated 6906 ± 897 cpm. In contrast, lymphocytes from normal individuals incorporated 7452 ± 1126 cpm. Ig synthesis of lymphocytes from active SLE in response to LPS stimulation was also less than that of normal individuals. The helper T‐cell function of active SLE, as examined by co‐culturing irradiated SLE lymphocytes with unirradiated normal lymphocytes, was normal. These results thus suggested that a defect of B lymphocytes exists in active SLE patients. This B‐cell defect and T suppressor cells apparently play an important role in the pathogenous of SLE.