CD4 and neoplasm: It is noteworthy that the immune cells including CD4+CD25+FOXP3+Treg cells, myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) type 2 are engaged in this mechanism by infiltrating into tumors and hindering antitumor immune responses of tumor antigen-specified CD8+ T cells and CD4+ T cells (14).