IGF-I ELISA

>Background:Insulin-like growth factors (IGF) I and II play a pivotal role in regulating the proliferation, differentiation and specific functions of many cell types (1-3). IGF-I is identical with Somatomedin C (Sm-C) (4) and has a molecular weight of 7649 Dalton (5). Its major regulators are growth hormone (GH) and nutrition (6), although its production in specific tissues is affected by a multitude of tropic hormones and other peptide growth factors. In contrast to many other peptide hormones, IGFs are avidly bound to specific binding proteins (IGFBP). The seven classes of IGFBPs which are known at present (7,8,22) either bind IGF-I and IGF-II with similar affinities or show a preference for IGF-II (9,10). A major problem of IGF-I measurement results from the interference of IGFBPs in the assay. Direct determinations in untreated serum samples (11) give false values because of the extremely slow dissociation of the IGF-I/IGFBP-3 complexes during the assay incubation.

Description:
The ELISA for IGF-I DEE020 is a so-called Sandwich-Assay. It utilizes two specific and high affinity antibodies for this protein. The IGF-I in the sample binds to the immobilized first antibody on the microtiter plate, the biotinylated and Streptavidin-Peroxidase conjugated second specific anti-IGF-I-Antibody binds in turn to the immobilized IGF-I. In the closing substrate reaction, the turn of the colour will be high specific catalysed, quantitatively depending on the IGF-I-level of the samples. In order to dissociate IGF-I from the IGFBPs, the samples must be diluted in an acidic buffer (Sample Buffer).The diluted samples are then pipetted into the wells, by this the pH-value will be neutralized. After neutralization of the samples, the excess IGF-II occupies the IGF-binding sites of the binding proteins, thus allowing the measurement of resulting free IGF-I. With this method, the IGFBPs are not removed, but their function and therefore their interference in the assay is neutralized. Due to the extremely low crossreactivity of the IGF-I antibody with IGF-II, the excess of IGF-II does not disturb the interaction with IGF-I. The test runs like a conventional ELISA using a Streptavidin-Peroxidase-Enzyme Conjugate.

Product features:
The kit contains reagents for 96 determinations;
Microtiter plate consisting of 12x8 (breakapart);
Microtiter plate reader at 450/≥590 nm;
Analytical sensitivity: 0,091 ng/mL;
IVD.