CD4 and cancer: The present study revealed that ADRA2C was closely associated with infiltration of multiple immune cells, such as B cells, CD4+ T cells, CD8+ T cells, NK cells, cytotoxic cells, etc. These findings may provide new insights for the application of ADRA2C in cancer immunotherapy, especially in ACC, BLCA, BRCA, OV, PAAD, STAD, TGCT, THYM, UVM, etc. On the other hand, investigations into immunoregulatory genes, such as CTLA-4, PD-1, PD-L1, and MHC molecules may provide novel insights into the discovery of immunotherapeutic agents for combating tumors 41.