CD4 and cancer: Under ideal conditions, the innate and adaptive elements of the immune system work together to eliminate cancer (often imperfectly) with regulatory (CD4+) and cytotoxic (CD8+) T cells, dendritic, natural killer cells (NK) and macrophages with a number of proteins secreted by immune activation, such as interferon gamma, interleukin 12 and tumor necrosis factor (TNF) working in harmony.