CD5 and Arthritis: There are two main regulatory B cell populations in mice: transitional B cells (CD19+CD21hiCD23hiCD1dhi) have been shown to prevent arthritis (86), and B10 B cells (CD19+CD5+CD1dhi) has been shown to maintain immune tolerance by inhibiting Th1/Th17 response and promoting Treg cell production in murine arthritis (87).