CD4 and systemic lupus erythematosus: We examined the autoimmune responses including AFC, GC, and CD4+ T cell responses in the absence of STAT4 in autoimmune-prone Sle1b mice (36, 37); TLR7-induced SLE-prone B6.Sle1b (Sle1b) mice (38); and spontaneous (Spt), SLE-prone FcyRIIB−/− mouse strain (39, 40).