title: Exploring the complementary selectivity of immunocapture and MS detection for the differentiation between hCG isoforms in clinically relevant samples.
abstract: Whereas numerous immunoassays have been developed to ensure detection of the entire spectrum of isoforms displayed by the human chorionic gonadotropin (hCG) molecule, significant variation has been demonstrated in how these isoforms are recognized by the antibodies in different immunoassays. The aim of this study was to establish a method using the dual selectivity of the immunoextraction and the mass spectrometry detection for the differentiation between various hCG isoforms in clinically relevant samples. Immunoextraction of endogenous hCG isoforms using a monoclonal antibody (E27) on a 96-well microtitier plate, followed by in-well tryptic digestion, and SIM monitoring of the selected signature peptides, resulted in the qualitative differentiation between several hCG isoforms in serum or urine. We conclude that the orthogonal selectivity conferred by the combination of immunoaffinity extraction and LC-MS analysis offers valuable complementary information to the conventional immunoassays.
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, Oslo, Norway.
authors.forename: Hanne
authors.initials: H
authors.lastname: Lund
authors.forename: Silje Bøen
authors.initials: SB
authors.lastname: Torsetnes
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Paus
authors.forename: Kjell
authors.initials: K
authors.lastname: Nustad
authors.forename: Léon
authors.initials: L
authors.lastname: Reubsaet
authors.forename: Trine Grønhaug
authors.initials: TG
authors.lastname: Halvorsen
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D015415:Biomarkers / Q000737:chemistry / Q000378:metabolism; D006063:Chorionic Gonadotropin / Q000097:blood / Q000737:chemistry* / Q000235:genetics / Q000652:urine; D002853:Chromatography, Liquid / Q000379:methods; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D013058:Mass Spectrometry / Q000379:methods*; D008969:Molecular Sequence Data; D009369:Neoplasms / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000235:genetics; D011247:Pregnancy; D020033:Protein Isoforms / Q000097:blood / Q000737:chemistry* / Q000235:genetics / Q000652:urine; D040901:Proteomics / Q000379:methods; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000379:methods
chemical_list: D000911:Antibodies, Monoclonal; D015415:Biomarkers; D006063:Chorionic Gonadotropin; D010455:Peptides; D020033:Protein Isoforms