Stimulation of human leukocytes by protein II+ gonococci is mediated by lectin-like gonococcal components

Abstract

We investigated the ability of carbohydrates, glycosidases, and concanavalin A to inhibit the stimulation of the human leukocyte oxidative burst by gonococci in the absence of serum. The gonococci used in this study contained protein II (P.II) outer membrane proteins, and neutrophil oxidative burst was measured by luminol-enhanced chemiluminescence (CL). The following carbohydrates inhibited CL induced by nonpiliated P.II+ gonococci: beta-D-glucosamine greater than N-acetylneuraminic acid (sialic acid) greater than mannose greater than alpha-methylmannoside greater than N-acetyl-beta-D-glucosamine greater than or equal to glucose greater than or equal to lactose. Fucose, galactose, or beta-D-galactosamine (all 100 mM) did not inhibit or slightly increased CL, indicating a specificity for the observed effects. Mannose and alpha-methylmannoside also inhibited induction of monocyte CL by P.II+ gonococci. Incubation of neutrophils with concanavalin A inhibited subsequent gonococcus-induced CL but not phorbol myristate acetate-induced CL. Treatment of neutrophils with alpha-mannosidase reduced subsequent gonococcus-induced CL greater than 99%, whereas such treatment of gonococci had no effect on their ability to induce neutrophil CL. Incubation of a P.IIb-containing variant of Neisseria gonorrhoeae FA1090 with anti-P.IIb monoclonal antibody inhibited subsequent stimulation of neutrophil CL in a dose-responsive manner, indicating a specific role for P.IIb in the stimulatory process. The data suggest that one or more lectin-like components on the surface of P.II+ gonococci mediate their ability to stimulate the oxidative burst of human phagocytes.