title: Measurement of pneumococcal capsular polysaccharide serotype-specific immunoglobulin G in human serum, a method for assigning weight-based units to proposed reference sera.
abstract: A direct method for measuring serotype-specific, class-specific antibody in proposed human reference sera is described. The assay uses a 125I-labeled, isotopically pure immunoglobulin G (IgG) as a primary standard in an antigen-antibody solid-phase enzyme immunoassay. From the measurement of specific radioactivity bound to the absorbed antigen, serotype-specific IgG concentrations and optical density values can be directly related to optical density and serotype-specific IgG values for the reference serum. We used this method to provisionally assign IgG concentrations in a pneumococcal reference serum to serotypes 1, 3, 6A, 12F, 14 and 23F. This assay was found to be reproducible; the coefficient of variation for duplicates was within 5%, and the day-to-day coefficient of variation was from 3 to 18% for all six serotypes. The assay provides a general method for standardizing human reference serum tools with respect to concentration of antigen-specific IgM-, IgA-, and IgG-subclass antibodies.
authors.affiliation: Arctic Investigation Program, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Anchorage, Alaska 99501, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Rudolph
authors.forename: A J
authors.initials: AJ
authors.lastname: Parkinson
mesh_terms: D000918:Antibody Specificity / Q000276:immunology; D016667:Bacterial Capsules / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000592:standards; D007074:Immunoglobulin G / Q000097:blood*; D007457:Iodine Radioisotopes; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae / Q000276:immunology*; D014894:Weights and Measures
chemical_list: D007074:Immunoglobulin G; D007457:Iodine Radioisotopes; D011135:Polysaccharides, Bacterial