CD4 and neoplasm: It is worth noting that the interaction between HLA‐II molecules (such as HLA‐DRA, HLA‐DRB1, HLA‐DRB5, HLA‐DQB1, HLA‐DPB1, HLA‐DPA1, HLA‐DMB and HLA‐DMA) and the receptor CD4 was exclusively detected in the cell communication between malignant cells from single‐primary tumours and Tregs.