CD4 and cancer: Cancer cell mediated activation of immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs), tumour associated macrophages (TAMs) and CD4+ T-regulatory cells (T-reg), is promoted through secretion and expression of immunosuppressive cytokines and membrane bound ligands (e.g., Programmed Death Ligand-1(PDL-1) or B7-1/2), that further hinder natural killer (NK) and T-cell anti-tumour response [142].