Measurement of the free alpha subunit of human glycoprotein hormones by a monoclonal antibody-based immunoradiometric assay, and further exploration of antigenic sites on the choriogonadotropin molecule

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · Clin. Chem. (Winston-Salem, N.C.); (United States)

OSTI ID:6173892

Norman, R J; Haneef, R; Buck, R H; Joubert, S M

Three monoclonal antibodies were raised against the free alpha subunit of choriogonadotropin (hCG); each recognized a different antigenic site on the molecule. One (antibody 42) preferentially bound to the alpha subunit when it was coupled to the beta subunit as dimeric choriogonadotropin (hCG), thyrotropin (TSH), lutropin (LH), or follitropin (FSH). Antibody 71 showed some cross-reaction with intact FSH; antibody 75 was more specific for the alpha subunit. All were of low affinity (10(-7) to 10(-8) mol/L), but when combined in immunoradiometric assays (IRMAS) they proved to be as sensitive as current radioimmunoassays involving polyclonal antibodies. Advantages of the combination of antibody 75 bound to the solid phase and antibody 71 as the radiolabeled antibody were: detection limit of at least 0.1 micrograms/L; linear dilution of serum and urine; insignificant cross-reaction with intact hCG, allowing direct assay in pregnancy fluids; and a coefficient of variation less than 3% over the reference interval for nonpregnant women. There was 4% cross-reaction with intact FSH, suggesting that the epitopes recognized by nos. 71 and 75 are more exposed in FSH and that perhaps there is less folding in this molecule than in intact hCG.

• Research Organization: Univ. of Natal Medical School, Congella, South Africa
• OSTI ID: 6173892
• Journal Information: Clin. Chem. (Winston-Salem, N.C.); (United States), Journal Name: Clin. Chem. (Winston-Salem, N.C.); (United States) Vol. 33:7; ISSN CLCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
ANTIBODIES
ANTIGENS
BIOCHEMICAL REACTION KINETICS
CONTROL
FSH
GONADOTROPINS
HORMONES
IMMUNOASSAY
IMMUNOLOGY
ISOTOPE APPLICATIONS
KINETICS
MAMMALS
MICE
MONOCLONAL ANTIBODIES
PEPTIDE HORMONES
PITUITARY HORMONES
PREGNANCY
QUALITY CONTROL
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNOLOGY
REACTION KINETICS
RODENTS
TRACER TECHNIQUES
VERTEBRATES