Neutrophil cytotoxicity induced by immune complexes prepared with cationized antibodies

Here we analyse the ability of soluble immune complexes (IC) prepared with cationized antibodies to induce cytotoxic responses mediated by neutrophils. While cationized IC induced high levels of cytotoxicity, control IC induced very low levels of response. Inhibition of cytotoxicity by catalase but not by three haemenzyme inhibitors suggests that oxygen-dependent but myeloperoxidase-independent mechanisms are responsible for cytolysis. While the response induced by control IC was enhanced by cytochalasin B and was not modified by colchicine, that induced by cationized IC was markedly inhibited by cytochalasin B and significantly enhanced by colchicine. Cytotoxicity induced by cationized IC was completely abrogated by monoclonal antibodies to Fc gamma RII. Using control IC, a partial inhibition was observed employing either anti-Fc gamma RII or anti-Fc gamma RIII monoclonal antibodies. Treatment of neutrophils with chemotrypsin or pronase significantly enhanced cytotoxicity induced by cationized IC but not by control IC. We also found that non-specific absorptive mechanisms appear to play an important role in the binding of cationized IC, but not control IC, to the neutrophil surface. The significance of these results is discussed.