Mitogenic responses to lipopolysaccharide by B lymphocytes from patients with systemic lupus erythematosus.

Peripheral blood lymphocytes from 43 patients with systemic lupus erythematosus (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 pathogenesis of SLE.