CD4 and myeloid sarcoma: Interestingly, gut commensal can induce Tregs in the gut [164]; the most prevalent capsular polysaccharide produced by B. fragilis, polysaccharide A (PSA), drives the transformation of CD4+ T cells to Foxp3 + Tregs which release IL-10 and suppress Th17 responses by activating Toll-like receptor 2 (TLR-2) and protects against MS [165].