Of note, multiple studies have demonstrated that CD5+ B cells are protective in cases of intestinal inflammation by generating natural antibodies against microbial flora[10] and producing IL-10.[11,12] Intestinal CD5+ B cells are also the main source of IgA secretion,[13,14] which can continuously protect the body from threat of infection by pathological bacteria and maintain a normal flora composition. This evidence concerns the gene CD5 and infection.