Tumor-specific targeting of T helper type 1 (Th1) cells by anti-CD3 x anti-c-ErbB-2 bispecific antibody

T helper type1 (Th1) or type2 (Th2) cells were induced from naive Th cells obtained from ovalbumin-specific T cell receptor (TCR) transgenic mice. Th1 cells producing interferon gamma (IFNgamma) exhibited stronger antigen-specific cytotoxicity against ovalbumin-(323-339)-peptide-pulsed A20 tumor cells than did Th2 cells. To develop a general method for applying antigen-nonspecific Th1 cells to tumor immunotherapy, we examined the targeting of Th1 cells to tumor cells using a bispecific antibody (bsAb) consisting of anti-(mouse CD3) mAb and anti-(human c-ErbB-2) mAb. When ovalbumin-specific Th1 or Th2 cells were cocultured with c-erbB-2-positive transfectants (CMS7HE), neither type of cell showed significant cytotoxicity or cytokine production in response to tumor cells. However, addition of bsAb resulted in the triggering of both Th1 and Th2 cells. Th1 cells showed higher levels of bsAb-dependent cytotoxicity against CMS7HE tumor cells than did Th2 cells. The targeting of Th1 cells to CMS7HE tumor cells by bsAb also triggered the production of cytokines such as IFNgamma, interleukin-2 and tumor necrosis factor alpha (TNFalpha). The released TNFalpha was demonstrated to be a critical cytolytic factor in bsAb-mediated cytotoxicity by Th1 cells. Finally, Th1 cells were demonstrated to show antitumor activity in vivo against human c-erbB-2-positive tumor cells implanted in nude mice. These results suggest that Th1 cells are useful effector cells for the application to adoptive tumor immunotherapy in conjunction with bsAb.