S100A9 and Autoimmunity: Others have found that a subset of B helper neutrophils capable of producing BAFF was significantly increased in autoimmune mice and people with autoimmune diseases (49) however, we found no evidence for differential levels of BAFF in S100a9-sufficient and –deficient NBWF1 mice, and thus a potential pathogenic mechanism by mature neutrophils in S100a9-deficient male mice remains unknown.