CYCLOHEXYLAMINE INHIBITS THE ADHESION OF LYMPHOCYTIC CELLS TO HUMAN SYNCYTIOTROPHOBLAST

We have previously shown that lymphocytic cells adhere to cultured syn cytiotrophoblast and that this may be important in the lymphocyte-medi ated infection of trophoblast with the human immunodeficiency virus (H IV). During the course of studies aimed at investigating the role of c ell surface carbohydrates in adhesion, it was discovered that a contam inant of commercial fucose-l-phosphate, dicyclohexylamine, inhibited M OLT-trophoblast adhesion. Dicyclohexylamine and the related compounds, cyclohexylamine and hexylamine, inhibited adhesion in a dose-responsi ve manner with half-maximal inhibition seen at about 4 mM. While the p resser effects of cyclohexylamine, the principal metabolite of cyclama te, are well known, this is the first report of an effect of this and related compounds on cell adhesion activity. The inhibitory effect was reversible and, at concentrations less than 25 mM, did not result in loss of cell viability. Several possible mechanisms of action of cyclo hexylamine were examined in an attempt to explain the effect on adhesi on. No evidence was found to suggest that the effects of cyclohexylami ne were due to inhibition of polyamine synthesis, increase in intracel lular Ca2+ concentration or to a lysosomotropic effect. The concentrat ions of cyclohexylamine used are within the range of plasma concentrat ions attainable in humans, raising the possibility that the in vitro e ffects described here may also occur in vivo. The results also suggest that caution should be used in the interpretation of results obtained from experiments where cell adhesion is blocked using exogenous monos accharides that are in the form of dicyclohexylammonium salts. Appropr iate controls must be included or, if possible, sodium, potassium or b arium salts should be chosen.