VSIR and asthma: Additionally, VISTA acts as a co-inhibitory receptor on T cells, significantly modulating antigen-specific CD4+ T cell responses and protecting mice from GVHD, acute hepatitis, and asthma (97).VISTA is primarily expressed on CD45+ cells located near tumors and is also present in the hematopoietic system, with notable expression in myeloid cell compartments (98).