Immunization with HER2 extracellular subdomain proteins induces cellular response and tumor growth inhibition in mice

We investigated cellular and protective immune responses in mice vaccinated with recombinant HER2 extracellular subdomains. Balb/C mice were immunized with recombinant full HER2 extracellular domain and subdomain proteins. Humoral and cellular immune response and antitumor effect was evaluated using a syngeneic mice tumor model. All recombinant proteins induced secretion of IL-4 and particularly IFN-γ and IL-17 cytokines. Challenging of immunized mice with stable 4T1-HER2 transfected cells resulted in partial but significant tumor growth inhibition in all groups of mice particularly those immunized with fHER2-ECD together with CPG. Our results suggest that the recombinant HER2-ECD subdomains induce mainly Th1 and Th17 responses, which seem to contribute to tumor growth inhibition in syngeneic mice.