Monoclonal antibodies against the free subunits of human chorionic gonadotrophin.
Discordant results on body fluid levels of human chorionic gonadotrophin (hCG) free alpha- and beta-subunits under physiological and pathophysiological conditions, prompted us to raise a total of 260 monoclonal antibodies (MCA) against free hCG-alpha, free hCG-beta, holo-hCG, human follicle-stimulating hormone and bovine luteinizing hormone; 153 MCA recognizing the human alpha-subunit and 28 reacting with hCG-beta were extensively analysed for their intra- and inter-species cross-reactivity with homologous hormones, and for the compatibility of epitopes recognized by them. The immunological topography of free hCG-alpha and free hCG-beta was resolved by these MCA, and epitope maps were designed. Six antigenic determinants on the free alpha-chain (alpha 1-alpha 6), clustered in three spatially distinct domains, and seven epitopes on the surface of free hCG-beta (beta 1-beta 7), could be distinguished. Strikingly, three alpha-chain epitopes (alpha 4, alpha 5 and alpha 6) were shared between various species, which is in contradiction to the concept of immunological species-specificity of alpha-subunits. Three determinants were found to be present only on the free subunits but not on holo-hCG (alpha 6, beta 6 and beta 7), and only two determinants (beta 1 and beta 7) were hormone-specific for hCG. Based on this information, an immunoenzymometric assay for the free alpha-subunit of human glycoprotein hormones was established, with a sensitivity of 1.3 pg/well and a cross-reactivity with holo-hCG of less than 0.005%.(ABSTRACT TRUNCATED AT 250 WORDS)
Berger
P
P
Immunoendocrinology Research Unit, Austrian Academy of Sciences, Innsbruck.
Klieber
R
R
Panmoung
W
W
Madersbacher
S
S
Wolf
H
H
Wick
G
G
D000911:Antibodies, Monoclonal / Q000276:immunology*; D006063:Chorionic Gonadotropin / Q000032:analysis / Q000276:immunology*; D018997:Chorionic Gonadotropin, beta Subunit, Human; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D015292:Glycoprotein Hormones, alpha Subunit / Q000032:analysis / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques; D010446:Peptide Fragments / Q000032:analysis / Q000276:immunology; D011863:Radioimmunoassay
D000911:Antibodies, Monoclonal; D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D000939:Epitopes; D015292:Glycoprotein Hormones, alpha Subunit; D010446:Peptide Fragments