Our study found that the interaction of PD-L1 and PD-1 in the hot to IMS phases shifts the peak, mainly in the area of close contact between T cells and tumor cells, and after this period, PD-L1 no longer has a major impact, therefore, in the immunotherapy of PCNSL, the medication time of a part of immune checkpoint molecule inhibitors is particularly important. The gene discussed is CD274; the disease is primary central nervous system lymphoma.