CD5 and Autoimmunity: Alternatively, CD5+ B regulatory cells may not be the sole mechanism mediating suppression of autoimmunity in B6.NZBc1c4 bicongenic mice, as a genetic locus that leads to decreased autoantibody production in a graft vs host autoimmunity model has been identified in the NZB-derived Sle2 region located between 115 to 128Mb [37,38].