159 SOLUBLE INTERCELLULAR CELL ADHESION MOLECULE 1 (sICAM-1) IN HUMAN MILK

Abstract

Cell adhesion molecules such as ICAM-1 are expressed on blood and endothelial cells and mediate cell-cell interactions e.g. in the initial stage of inflammation. These molecules are also present in soluble form in various biological fluids. They are not only discussed as markers for the activation of cells, but also as regulators for inflammatory processes. Cell adhesion molecules in milk could be of importance as immune factors for the human milk fed infant. We analyzed milk from women (n = 10) after preterm delivery (33 ± 1 wk of gestation) for sICAM-1. After SDS-PAGE and Western blotting, milk proteins were incubated with monoclonal antibodies for ICAM-1. For quantitation, 5 - 6 milk samples per mother during the first month of lactation were subjected to a sandwich ELISA for sICAM-1. ICAM-1 was detected in all human milk samples we tested. The molecular weight of positive reacting proteins was about 80 kD which is in agreement with the molecular weight reported for sICAM-1 in serum. The concentrations of sICAM-1 during the first month of lactation varied widely, but were within the range reported for serum concentrations. In 7 of the 10 mothers, we determined concentrations in milk (40 - 350 ng/ml) that would be considered normal in serum. In 3 women, however, sICAM-1 in milk was found to be in a higher range (690 - 1500 ng/ml) which indicates an activated stage of corresponding cells. In conclusion, the concentrations of sICAM-1 in human milk were found to be on a level that would justify speculations about inflammation suppressive functions of sICAM-1 in human milk fed infants.