title: Isotype distribution and bactericidal activity of antibodies after immunization with Haemophilus influenzae type b vaccines at 18-24 months of age.
abstract: The serum antibody response to Haemophilus influenzae type b capsular polysaccharide or its protein conjugate vaccine (PRP and PRP-D, respectively) was studied in 28 children initially immunized at the age of 24 mo with either vaccine and in 10 children immunized for the third time with PRP-D at the age of 18 mo. The methods used were isotype-resolving enzyme immunoassay, Farr-type radioimmunoassay, and the in vitro bactericidal activity (BCA) test. Immunization with PRP evoked a higher proportion of IgA antibodies than did either the first or third dose of PRP-D, whereas the latter vaccine evoked a somewhat higher IgG response, but the differences were not statistically significant. In all groups the IgG antibody responses were predominantly IgG1, with the mean proportions being 82.2%, 84.2%, and 65.9% in the PRP, first-dose PRP-D, and third-dose PRP-D groups, respectively. Postimmunization antibodies were functionally active in the BCA test.
mesh_terms: D000907:Antibodies, Bacterial / Q000032:analysis* / Q000096:biosynthesis / Q000276:immunology; D016667:Bacterial Capsules; D001428:Bacterial Vaccines / Q000276:immunology*; D001770:Blood Bactericidal Activity; D018073:Haemophilus Vaccines; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007117:Immunization, Secondary; D007124:Immunoenzyme Techniques; D007070:Immunoglobulin A / Q000032:analysis / Q000096:biosynthesis; D007074:Immunoglobulin G / Q000032:analysis / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000032:analysis / Q000096:biosynthesis; D007136:Immunoglobulins / Q000032:analysis* / Q000096:biosynthesis / Q000276:immunology; D007223:Infant; D011135:Polysaccharides, Bacterial; D011237:Predictive Value of Tests; D011863:Radioimmunoassay
chemical_list: D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007136:Immunoglobulins; D011135:Polysaccharides, Bacterial