Elimination of Complement Interference in Immunoassay of Hyperglycosylated Human Chorionic Gonadotropin

[摘要] To the Editor:Hyperglycosylated human chorionic gonadotropin (hCG-h)1 is the major form of hCG occurring in early pregnancy and trophoblastic disease, whereas the glycans are smaller in hCG produced later in pregnancy (1, 2). hCG-h can be measured by immunoassays based on monoclonal antibody B152, which reacts with a type 2 core O-glycan attached to Ser132 and surrounding peptide structures but not with hCG lacking this glycan or having a type 1 core O-glycan in this position (3). In early pregnancy, reduced hCG-h concentrations in urine have been associated with early pregnancy loss (2), whereas increased concentrations at 9 to 12 weeks have been associated with Down syndrome (1). A high proportion of hCG as hCG-h is useful in diagnosing malignant trophoblastic disease (4). These results need to be confirmed, but an earlier-version assay for hCG-h is not presently available (5). We developed a time-resolved immunofluorometric assay that uses B152 and found that serum contains factors that interfere with the assay to cause falsely low results. We demonstrated B152 to be an IgG2a antibody (Mouse Monoclonal Isotype Kit; Serotec, http://www.abdserotec.com), which interacts with complement to decrease its binding …

[学科分类] 过敏症与临床免疫学