CD4 and breast cancer: Previous reviews have summarized that protumorigenic and pro-inflammatory immune cells in the tumor microenvironment (TME) in BC consist of myeloid-derived suppressor cells (MDSCs), M2 macrophages, neutrophils, Th2 CD4+, Th17 CD4+, and FoxP3+ CD4+ T cells (T-regs) as well as T helper cells of type 1 (Th1) CD4+, CD8+ cytotoxic T lymphocytes (CTLs), M1 macrophages, dendritic cells (DCs), and natural killer (NK) cells, respectively (7, 8).