CD4 and neoplasm: To demonstrate whether T cells were involved in the antitumor responses induced by the vaccine, CMS5-VP1 tumor-bearing mice were immunized with VP1/CRA following depletion of CD3+ , CD4+ or CD8+ T cells by administrating anti-CD3, anti-CD4, or anti-CD8 monoclonal antibodies at the day before immunization, respectively (Fig. 5a).