VSIR and experimental autoimmune encephalomyelitis: In addition, overexpression of V-domain Ig-containing inhibitor of T cell activation (VISTA) results in the defect of T-cell activation, proliferation, and cytokine production, but the blockade of VISTA has been found to enhance T-cell responses and exacerbate the development of experimental autoimmune encephalomyelitis in vitro (8, 9).