CD4 and neoplasm: Naïve CD4+T cells (Th type 0, Th0) can be activated by the encounter with a tumour antigen via peptide/MHC class II TCR and differentiate into Th type 1 (Th1) and Th type 2 (Th2) cells, depending on the intensity of stimulation and presence of certain cytokines and other factors (Figure 1) [17].