The negative costimulatory molecules such as CTLA-4, PD-1, T cell immunoglobulin, and mucin domain-3 and lymphocyte-associated gene 3 are expressed in different immune cell types, including cytotoxic T cells, B cells, natural killer cells, monocytes, tumour-associated macrophages, myeloid-derived suppressor cells and dendritic cells exhibiting immunosuppressive functions. Here, PDCD1 is linked to neoplasm.