IL17A and immune system disorder: Vγ4T cells, a cell type that plays an important role in immune diseases, is the main source of IL-17 in the early stage of the immune response (12, 31), and we observed that MSCs expressing HVEM significantly inhibited IL-17 and IFN-γ secretion from Vγ4T cells and the proliferation of Vγ4T cells when co-cultured, and also released the inhibitory effect of Vγ4T cells on MSCs proliferation during co-cultured.