Immune stimulatory and anti-tumor properties of anti-CD3 and BAT monoclonal antibodies: a comparative study.

A novel monoclonal antibody raised to Daudi cell membranes was found to exhibit immune stimulatory and anti-tumor properties. The activity of this antibody (BAT) which also binds T cells was compared to that of anti-CD3. Anti-CD3 reacts with the T cell receptor complex, induces cell proliferation, and cytolytic activity in vitro and also manifests in vivo anti-tumor effect against murine tumors. Comparison of the two antibodies demonstrates similar induction in vitro of splenocyte proliferation and cytolytic activity. Both BAT and anti-CD3 antibodies manifest anti-tumor activity in mice bearing B16 melanoma. They differ however in the timing of antibody administration post-tumor inoculation which is most effective in eliciting the anti-tumor effect. Whereas BAT is most effective when administered 10 to 14 days post-tumor inoculation, anti-CD3 is effective at an early time. Data also indicate that BAT synergises with tumor cells in eliciting cell proliferation in vitro. In contrast, this effect could not be demonstrated with anti-CD3. The properties of BAT may be of advantage in its potential clinical use.