An immunoenzymatic method to measure IGF-1 in milk

Insulin-like Growth Factor 1(IGF-1) is a proteic hormone of 6,5 kD that plays a key role in the somatotropic axis. It is secreted by a number of tissues in response to stimuli of different origin, among which is the one induced by somatotropin, of which IGF-1 is the main biological mediator. IGF-1, besides being involved in the regulation of some tissue specific functions, also participates in regulation of the cell cycle, inhibiting the processes of apoptosis and stimulating cell proliferation. Moreover, IGF-1 has been described by some authors as a potential tumoral promoter. Regarding public health, the main concerns associated with treatment of dairy cows with recombinant somatotropin (rbST) to increase milk yield (forbidden in the EU with the Dec.99/218CE) is due to augmentation of the IGF-1 level in milk as a response to the higher concentration of circulating somatotropin. Our work consisted of developing a sandwich ELISA enabling quantification of IGF-1i n milk with a low-dilution sample pre-treatment.