CD4 and neoplasm: Decreased infiltration of the tumor by CD4+ and CD8+ T cells and the increased presence of regulatory T cells as well as TH2 cytokines (IL [interleukin]-4, IL-5), transforming growth factor (TGF)-β, and IL-10, also lead to an immunosuppressive environment in the tumor (Figure 3A) [64,68,70,71].