When patients progressed to a high-risk disease state, partly due to insufficient function of cytotoxic T cells, partly due to increased expression of immunosuppressive molecules such as PD-1, PD-L1 and Treg cells, which resulting in the escape of immune response and induction of immunological tolerance, promoted the progress of MDS to the high-risk stage [32]. The gene discussed is CD274; the disease is myelodysplastic syndrome.