Covalent conjugates of monoclonal antibody and cobra venom factor mediate specific cytotoxicity via alternative pathway of human complement activation.

Because of lack of unspecific toxicity autologous serum is the optimal source of complement for in vitro cell depletion in human bone marrow transplantation. Covalent binding of cobra venom factor to an antibody leads to a specific complement activating conjugate with cytolytic potential independent of the capacity of the antibody to fix complement itself. Therefore this conjugation allows the use of various sera, including human as the source of complement. The kinetics of cobra venom factor-initiated cytolysis is compatible with in vitro treatment of bone marrow prior to transplantation.