Located at the extra-follicular clusters of both lupus-prone MRL-Faslpr/lpr mice and B6.Sle1.Sle2.Sle3 (TC) mice, RF B cells can differentiate into RF plasmablasts with the immunization of anti-chromatin IgG2aa ICs through TLR9 dependent pathway [111,112]. The gene discussed is TLR9; the disease is systemic lupus erythematosus.