CD4 and cancer: It is likely that the generation of a potent CD4+ T cell-dependent anti-tumor response is the immunological driver behind beneficial clinical responses to cancer, and that the provision of CD4+ T cell help to CD8+ T cells and B cells generates further positive and negative amplification of anti-tumor immunity, respectively, resulting in eventual control of tumor growth by a combination of CD4+ and CD8+ T cells, despite the negative effects of B cells.