In fact, acidity was described to shorten the lifespan or inhibit the proliferation of CD4+ and CD8+ Cytotoxic T Lymphocytes (CTLs), Dendritic cells (DCs), and Natural Killer (NK) cells [16], whereas hypoxia could limit the level of M2 macrophages, T cells, and NKs, thus negatively affecting the immune system response and the consequent cancer aggressiveness [17]. Here, CD4 is linked to cancer.