IL2 and neoplasm: CD4+ cells play their role in antitumor immune responses by providing cytokines such as interleukin-2 (IL-2) (for effective CTL development and clonal expansion of activated CTLs) [49], TNF, and IFN-γ (that can boost cellular components of the innate immunity (macrophages and NK cells), increasing tumor cell class I MHC expression and sensitivity to lysis by CTLs) [50, 51].