INVOLVEMENT OF CD11B CD18 IN ENHANCED NEUTROPHIL ADHESION BY FC-GAMMARECEPTOR STIMULATION/

Neutrophils showed a rapid and transient adhesion to immunoglobulin G (IgG)-coated plates compared with their adhesion to bovine serum album in (BSA)-coated plates: the adhesion reached a peak after 15 min of in cubation and then gradually returned to almost the basal state in 60 m in. The addition of monomeric IgG or anti-Fc gamma RII monoclonal anti body (mAb) (IV.3) suppressed the increase in adhesion, whereas anti-Fc gamma RIII mAb (3G8) was hardly effective, indicating that the intera ction of Fc gamma R, especially Fc gamma RII, with coated IgG is invol ved in the process. Adhesion was also blocked by cytochalasin B, sugge sting that functional actin filament structures are crucial. Protein k inase inhibitors, erbstatin and genistein, inhibited the adhesion in a dose-dependent manner. The adhesion was inhibited by anti-CD11b (M1/7 0) and anti-CD18 (MHM23, TS1/18) mAbs. Moreover, neutrophils from a pa tient with complete leukocyte adhesion deficiency syndrome did not sho w increased adhesion to IgG-coated plates. The adhesion of neutrophils to fibrinogen- and BSA-coated plates was also increased when Fc gamma R was stimulated in the fluid phase with soluble aggregated IgG, whic h was also inhibited by anti-CD11b mAb. Stimulation of neutrophil Fc g amma R with soluble aggregated IgG enhanced the expression of CD11b in concert with the enhanced adhesion. These data collectively suggest t hat stimulation via Fc gamma R evokes a tyrosine kinase-dependent and actin filament-dependent intracellular signal that enhances the specif ic and nonspecific adhesive activity of neutrophils, presumably throug h the activation of CD11b/CD18.