A monoclonal antibody-inhibiting FMLP-induced chemotaxis of human neutrophils

A monoclonal IgG1 antibody, termed NCD3, was raised against human neutrophils and has been shown to inhibit neutrophil chemotaxis. NCD3 displayed a considerable degree of stimulus specificity in that it inhibited N-formyl-methionyl-leucyl-phenylalanine- (FMLP) induced chemotaxis up to 80%, C5a and zymosan-activated plasma induced chemotaxis by only 20% and had no effect on leukotriene B4- (LTB4) or casein-mediated chemotaxis. NCD3 did not inhibit granule enzyme release from neutrophils in response to stimulation by various secretagogues, including FMLP, in the presence or absence of cytochalasin B (CB). Neutrophil phagocytosis of 51Cr-labeled opsonized sheep erythrocytes (51Cr-EAC) and superoxide anion (O2-) production in response to FMLP or phorbol myristate acetate (PMA) stimulation were not affected by pretreating cells with NCD3. Divalency of NCD3 was necessary for inhibition of chemotaxis, suggesting a requirement for cross-linking of the antigenic determinants on the neutrophil membrane surface.