HUMAN-MILK PROTEINS MAY INTERFERE IN ELISA MEASUREMENTS OF BOVINE BETA-LACTOGLOBULIN IN HUMAN-MILK

It is widely believed that cow's milk proteins ingested by the mother, in particular beta-lactoglobulin (beta-LG), can pass into breast milk and thus sensitize predisposed infants. However, studies to evaluate bovine beta-LG in human milk have given conflicting results. The aim o f this study was to analyse the correlation between the amount of cow' s milk in the mother's diet and the presence of bovine beta-LG in brea st milk. Human milk samples from 14 healthy non-atopic women on diets with different cow's milk contents were examined. The total concentrat ion of bovine beta-LG or beta-LG immune-like proteins (beta-LGIP) was determined by enzyme-linked immunosorbent assay (ELISA). Two separatio n procedures utilizing ELISA plates and an affinity chromatography col umn were set up to identify the human whey components recognized by th e anti-beta-LG antibodies. beta-LGIP reactivities of milk from three g roups on different diets were not significantly different. After split ting the antigen-antibody complexes, three main protein components, hu man lactoferrin, human beta-casein and human alpha-lactalbumin, were i dentified. This study would suggest that, at least in healthy subjects , false-positive results in ELISA determinations of bovine beta-LG in human milk might be due to cross-reactions between polyclonal antibodi es and different protein antigens.