title: Bactericidal activity for Neisseria meningitidis in properdin-deficient sera.
abstract: We investigated serum bactericidal reactions against Neisseria meningitidis (serogroups A, B, C, D, Y, W-135, 29E, X, and Z) in the sera of two healthy adults with properdin deficiency. Bactericidal reactions mediated via the classic complement pathway (unchelated system) were not impaired in properdin-deficient serum. The properdin-deficient sera supported alternative pathway-mediated killing (Mg++EGTA-chelated system) of some, but not all, of the strains investigated. Vaccination of the properdin-deficient individuals with serogroup A and C polysaccharide clearly increased the concentrations of antibody to meningococci. At least some of the antibodies induced by vaccination supported the bactericidal activity of properdin-deficient serum. Some antibodies to meningococci, probably of the IgM class, promoted alternative pathway-mediated bactericidal reactions in the absence of properdin. By contrast, presensitizing meningococci with IgG enhanced the alternative pathway-mediated reactions, but this was strictly a properdin-dependent effect.
mesh_terms: D000907:Antibodies, Bacterial / Q000032:analysis / Q000276:immunology; D001770:Blood Bactericidal Activity; D003170:Complement Pathway, Alternative; D003171:Complement Pathway, Classical; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008297:Male; D009345:Neisseria meningitidis / Q000276:immunology*; D011414:Properdin / Q000172:deficiency* / Q000494:pharmacology; D014611:Vaccination
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D011414:Properdin