Bimodal effects of MVE-2 on cytotoxic activity of natural killer cell and macrophage tumoricidal activities

Abstract Maleic anhydride divinyl ether of molecular weight 15,500 (MVE-2) increased the tumoricidal activity of NK cells and Mφ in a dose-dependent manner with the peak response of both effector cells occurring 3 days following treatment. Both effector cell responses were sustained for over 7 days following one injection. However, repeated injections with MVE-2 led to a hyporesponsiveness of NK cells whereas Mφ activity remained high. Poly ICLC, but not C. parvum , reconstituted NK cell activity in mice hyporesponsive to MVE-2. Significant antitumor response was achieved when tumor cells were inoculated at the peak time of effector cell response, indicating the in vivo role of NK and/or Mφ in exerting a tumoricidal effect.