CD19 and Autoimmunity: B1 cells, which have long been implicated in the development of autoimmunity and production of autoantibodies (41), were identified in both IL-14αTG and C57BL/6 mouse SMGs; however, no significant differences were observed between genotypes with regards to either B1a (CD19+, B220−, CD5+) or B1b (CD19+, B220−, CD5−) cell subsets (Figure 2B).