THE LEUKOCYTE SURFACE-ANTIGENS CD11B AND CD18 MEDIATE THE OXIDATIVE BURST ACTIVATION OF HUMAN PERITONEAL-MACROPHAGES INDUCED BY TYPE-1 FIMBRIATED ESCHERICHIA-COLI

Analysis by immunofluorescence-activated cell sorting of human peritoneal macrophages from patients undergoing intermittent peritoneal dialysis revealed that they express the CD11/CD18 surface antigens, with CD11b and CD18 as the predominant ones. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of immunoprecipitates obtained from lysates of I-125-labeled macrophages with rabbit polyclonal antibodies against the CD11a-c/CD18 complex or against CD18, revealed four radioactive bands corresponding to CD11a, CD11b, CD11c, and CD18. Monoclonal antibodies against CD11b and CD18 inhibited by 80 and 90% respectively, the oxidative burst activation of the macrophages by type 1 fimbriated Escherichia coli, whereas monoclonal antibodies against CD11a, CD11c, and CD43 were without effect. Our results suggest that CD11b and CD18 (receptors for C3bi) serve also as receptors for mannose-specific E. coli on human peritoneal macrophages and may be involved in the lectinophagocytosis of the bacteria by these cells.