Assays for IGF binding proteins.

Growing interest in IGF binding proteins and their roles in the modulation of IGF actions has prompted several laboratories to establish immunological assays to measure these proteins. Three distinct IGF binding proteins, referred as IGFBP-1, IGFBP-2 and IGFBP-3, have so far had their cDNAs cloned and sequenced. The availability of purified proteins and the development of polyclonal and monoclonal antibodies now allow specific quantitation of different IGFBP classes. This brief review will address on the current progress in the immunological assays of IGFBPs. The importance of the sensitivity, the reproducibility, and the standardization of the assays is discussed. Some additional information, like levels in amniotic fluid and serum of healthy adults and children, is given.