To evaluate further the role of BCMA on the expression of BAFF in autoimmunity, we studied the BAFF-producing innate immune cells in spleens of female naïve C57BL/6 (WT) mice and congenic lupus-prone B6.Faslpr/J mice, and compared mice sufficient or deficient in the gene Tnfrsf17 that encodes BCMA. The gene discussed is TNFSF13B; the disease is systemic lupus erythematosus.