ASSIGNMENT OF NEISSERIA-MENINGITIDIS SEROGROUP-A AND SEROGROUP-C CLASS-SPECIFIC ANTICAPSULAR ANTIBODY CONCENTRATIONS TO THE NEW STANDARD REFERENCE SERUM CDC1992

A new standard meningococcal reference serum designated CDC1992 was pr epared to replace meningococcal reference sera ECG and PB-2, which are not available in sufficient quantities for continued use as primary r eference sera. CDC1992 was prepared from 14 healthy adult volunteers w ho underwent plasmapheresis 4 to 12 weeks postvaccination with a singl e dose of a Neisseria meningitidis quadrivalent polysaccharide vaccine , Total and/or class-specific meningococcal serogroup A and C anticaps ular antibody concentrations (in micrograms per milliliter) were assig ned to CDC1992 by using homologous and heterologous enzyme-linked immu nosorbent assay (ELISA) formats. The reference serum ECG was used as a reference standard to assign total anticapsular antibody concentratio ns to CDC1992 by a homologous ELISA format. A heterologous ELISA forma t, with the Haemophilus influenzae type b standard reference serum FDA 1983, was used to assign total and class-specific antibody concentrat ions to CDC1992. Alkaline phosphatase-labeled mouse anti-human monoclo nal antibody conjugates were used as secondary antibodies in both ELIS A formats. The total, immunoglobulin G (IgG), IgA, and IgM antibody co ncentrations, assigned to CDC1992 for serogroup A were 135.8, 91.8, 20 .1, and 23.9 mu g/ml, respectively, and those for serogroup C were 32. 0, 24.1, 5.9, and 2.0 mu g/ml, respectively. Meningococcal serogroup A and C antibody concentrations were in good agreement when homologous and heterologous ELISA format results were compared. Total and class-s pecific serogroup A and C antibody concentrations were determined in s ix adult quality control serum samples from the Centers for Disease Co ntrol and Prevention by using the homologous ELISA and our assigned an tibody concentrations for CDC1992. Antibody concentrations in referenc e sera ECG and PB-2 were measured in order to provide a historical lin k to previous studies. The general acceptance of CDC1992 as the standa rd reference serum and the assigned antibody concentrations will allow investigators to compare antibody levels in serum to those in a singl e reference preparation.