P2RY12 and multiple sclerosis: However, a more recent study did show that P2Y12 deficiency did not influence cell differentiation and proliferation of CD4+ T cells in vitro [18] while the authors report a higher level of T helper 17 (Th17) cells in P2Y12-knockout (KO) mice, in the animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE) [18].