title: Physical mapping of human insulin-like growth factor-I using specific monoclonal antibodies.
abstract: The primary structure of recombinant human (h) insulin-like growth factor-I (IGF-I) epitopes recognized by a panel of 28 monoclonal antibodies (mAbs) is characterized. Pairwise mAb epitope mapping defines eight 'epitopic clusters' (I-VIII) which cover nearly the entire solvent-exposed IGF-I surface. Monoclonal antibody reactivity with 32 overlapping synthetic peptides and with IGF-I mutants is used to associate these epitopic clusters with the probable primary IGF-I sequences recognized. Epitopic cluster I involves residues in the C-domain and the first alpha-helix of the A-domain; clusters II, V and VII involve principally the B-domain; clusters III and IV map to amino acid sequences (55-70) and (1-13) respectively; cluster VI includes the A- and B-domains; and cluster VIII involves mainly the C-terminal part of the B-domain. Data indicate that this mAb panel defines 14 distinct IGF-I epitopes. The specific inhibition of HEL 92.1.7 IGF-I-promoted proliferation by these mAbs was explored. Direct correlation between mAb affinity and inhibitory activity was observed except in the case of clusters III- and VIII-specific mAbs. Finally, the combination of epitopic cluster I and II mAbs detect 0.5-10 ng/ml hIGF-I in a sandwich immunoassay, with no IGF-II crossreactivity. These anti-IGF-I mAbs are, therefore, useful for both the inhibition of IGF-I mitogenic activity and for the quantification of this growth factor. The potential use of this mAb panel in tumor cell growth control is discussed.
authors.affiliation: Department of Immunology and Oncology, CSIC, Universidad Autonoma de Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Mañes
authors.forename: L
authors.initials: L
authors.lastname: Kremer
authors.forename: B
authors.initials: B
authors.lastname: Vangbo
authors.forename: A
authors.initials: A
authors.lastname: López
authors.forename: C
authors.initials: C
authors.lastname: Gómez-Mouton
authors.forename: E
authors.initials: E
authors.lastname: Peiró
authors.forename: J P
authors.initials: JP
authors.lastname: Albar
authors.forename: I B
authors.initials: IB
authors.lastname: Mendel-Hartvig
authors.forename: R
authors.initials: R
authors.lastname: Llopis
authors.forename: C
authors.initials: C
authors.lastname: Martínez
mesh_terms: D000911:Antibodies, Monoclonal; D018604:Epitope Mapping; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D007334:Insulin-Like Growth Factor I