CD4 and myeloid sarcoma: Cekanaviciute and colleagues identified a reduction in the bacterial genera Parabacteroides distasonis in MS patients and showed that P. distasonis exposure increases the differentiation of IL-10+ Tregs from healthy donor PBMCs in vitro. Moreover, in vivo monoclonization of germ free (GF) mice with P. distasonis significantly increased the amount of IL-10+ CD4+ T cells in the spleen and mesenteric lymph nodes (94).