VSIR and Autoimmunity: V-Domain Ig Suppressor of T Cell Activation (VISTA) is expressed on several immune cells, including CD11b+ myeloid cells, naïve CD4+ and CD8+ T cells, CD4+ Foxp3+ Treg cells, and TCRγδ T cells, and negatively regulates T cell-mediated autoimmunity and antitumor immunity85.