By examining immune checkpoints such as PD-1/PD-L1, CTLA-4/CD86, and CD200R/CD200 in different blood lymphocyte subpopulations, we aim to extract valuable insights that may improve not only our understanding of these diseases but also contribute to improving treatment conditions and the occurrence of subsequent complications and the development of hematological cancers. The gene discussed is CD200; the disease is hematopoietic and lymphoid cell neoplasm.