IGFBP-3 ELISA (Bioactive)

All currently existing IGFBP-3 immunoassays use the binding of specific anti-IGFBP-3 antibodies for signal generation and thus IGFBP-3 quantification. The failure of differentiation between complete IGFBP-3 molecules and their respective fragments (derived physiologically due to the different proteases activities) is unavoidable in this system. Because one molecule IGFBP-3 can be cleaved in several fragments often false high quantitative values are measured. Based on this methodology it is not possible to differentiate between high IGFBP-3 levels in fact, or, a high degree of fragmentation. The incidental attempts to use monoclonal antibodies with a binding region represented only by the intact IGFBP-3 molecule are indirect, imprecise and insufficient. The activities of all effective proteases, which have different sites of action and therefore generate different kind of fragments, are disregarded. IGFBP-3, however, enables to determine the real functional and effective bioactive IGFBP-3, functional in terms of binding ability of the mainly interesting natural ligand, namely IGF-I.