CD8A and neoplasm: For example, MHC-I offer CD8+T lymphocytes cell antigens, such as from its protein and virus protein antigen, and extracellular antigen by MHC II usually provided to CD4+T lymphocyte, loss of MHC-I during the process of tumor formation is one typical method that cancer cells evade monitoring of CD8+T cells, NK cells express to identify MHC-I molecules-inhibition of cell surface receptors, and eliminate cannot fully express a large number of MHC-I molecular targets [24–26].