CD4 and neoplasm: TICs are functionally split into two categories—(i) tumour-cell-growth inhibition, including CD8+ T, Th1 CD4+ T, Th9 CD4+ T, plasma, memory B, NK cells, and DCs; and (ii) tumour-cell-growth or immune-escape stimulation, including Treg, Breg, macrophage M2, and myeloid-derived suppressor cells (MDSCs) [21,22].