Interleukin 17 acts in synergy with B cell–activating factor to influence B cell biology and the pathophysiology of systemic lupus erythematosus

How interleukin 17 influences B cell biology is unclear. Bonnefoy-Bérard and colleagues find that interleukin 17 alone or in combination with B cell–activating factor controls the survival, proliferation of human B cells and their differentiation into immunoglobulin-secreting cells. Studies have suggested involvement of interleukin 17 (IL-17) in autoimmune diseases, although its effect on B cell biology has not been clearly established. Here we demonstrate that IL-17 alone or in combination with B cell–activating factor controlled the survival and proliferation of human B cells and their differentiation into immunoglobulin-secreting cells. This effect was mediated mainly through the nuclear factor-κB-regulated transcription factor Twist-1. In support of the relevance of our observations and the potential involvement of IL-17 in B cell biology, we found that the serum of patients with systemic lupus erythematosus had higher concentrations of IL-17 than did the serum of healthy people and that IL-17 abundance correlated with the disease severity of systemic lupus erythematosus.