CD4 and neoplasm: Interestingly, Villareal et al. demonstrated that IL-33 can be an effective adjuvant when combined with an HPV16 E6/E7-encoded DNA vaccine, enhancing both antigen specific CD4+ and CD8+ IFN-γ+ T cells, and antigen specific IgG concentration in the serum, leading to regression of established TC-1 tumor in mice (23).