CD4 and cancer: Moreover, it is reported that MHC class II-restricted response is required for augmented immune-mediated elimination of tumors 23, 27; CD4+ Th cells help sustain the cytolytic function and promote the memory commitment of CD8+ T cells during infection, cancer and immunization 28-30; and MHC class I tumor immunogenicity was essential for triggering tumor-directed CD4+ T cells, while tumor-specific CD8+ T cell response requires Th1-polarized CD4+ Th cells for efficient tumor suppression 31.