Neutrophil Chemotaxis Induced by Immune Complexes

In the current work we have analyzed the ability of different soluble immune complexes (IC) prepared with IgG antibodies to induce neutrophil chemotactic responses in vitro. While, in all cases, IC were able to induce neutrophil migration in a concentration-dependent fashion, IgG antibodies alone were completely unable to induce locomotor responses. Checkerboard analysis indicated the chemotactic nature of motility. On the other hand, chemotaxis induced by IC was markedly inhibited by IV.3, a monoclonal antibody (mAb) to FcγRII, slightly reduced by 3G8 F(ab′)2, a mAb to FcγRIII, and nearly abrogated by both mAbs. The impact of IC on neutrophil migration induced by FMLP was also studied. We found that when a suboptimal concentration of FMLP was employed, the simultaneous addition of IC increased the migration acting in additive form. The significance of these results is discussed.