CD4 and neoplasm: To achieve the immunosuppression, mesenchymal stromal cells can express factors that manipulate different aspects of the immune system including: a decrease in CD8+ T cells and NK cells; an increase in immunoregulatory CD4+ T cells accompanied by increased Th2 and decreased Th1 cytokines [251]; CCL2-CCR2, IL6, and IL10-mediated infiltration and polarization of macrophages into a alternatively activated, tumor-promoting phenotype [57,195]; and the CXCL1/CXCL2/CXCL5-CXCR2-dependent recruitment of tumor-suppressive neutrophils [58].