title: Characterization of the bactericidal antibody response against Haemophilus influenzae.
abstract: Rabbits were used in a study of the bactericidal (BC) antibody response against Haemophilus influenzae of types a and b and their respective non-capsulated variant strains. Previously described methods, complement fixation and indirect hemagglutination, were used for comparison. A bactericidal antibody response was demonstrable within a week after the primary immunization against capsulated as well as non-capsulated bacteria. After the hyperimmunization course the BC titres against noncapsulated bacteria were about 1:4,000, while the BC titres against the capsulated - type a and b-strains reached levels of no less than 1:30,000. Samples of separated hyperimmune sera showed BC activity in IgM- as well as IgG-containing fractions, whereas the BC activity of primary response samples was demonstrable mainly in IgM-containing fractions. The BC effect on non-capsulated bacteria of primary response samples were more heat labile than those obtained after hyperimmunization. In immune sera a crossreactive BC activity was demonstrable on non-capsulated bacteria, the titre being 32-64-fold lower than that of the homologous activity.
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D000937:Antigen-Antibody Reactions; D001770:Blood Bactericidal Activity; D002473:Cell Wall / Q000276:immunology; D003168:Complement Fixation Tests; D003429:Cross Reactions; D006193:Haemophilus influenzae / Q000276:immunology*; D006386:Hemagglutination Tests; D007074:Immunoglobulin G / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D011817:Rabbits
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007075:Immunoglobulin M