NEOGLYCOSYLATED LIPOSOMES AS EFFICIENT LIGANDS FOR THE EVALUATION OF SPECIFIC SUGAR RECEPTORS ON MACROPHAGES IN HEALTH AND IN EXPERIMENTAL LEISHMANIASIS

Receptors interacting with terminal sugars as ligands are involved in the binding of Leishmania donovani promastigotes to the macrophage sur face and their subsequent internalization. Mannose and glucose are spe cifically involved in the binding process. Decreased binding occurs to macrophages already infected with L. donovani either in vivo or in vi tro. When mannose- or glucose-bearing liposomes are used as ligands th e binding shows similar trends and the percentage inhibition of bindin g with mannose-bearing liposomes increases when compared to that for t he glucose-bearing ones. The decreased binding of the ligand seems to be due to a decrease in the number of receptors after infection. The a ffinity of the ligands for the binding sites either on the normal macr ophages or on the infected macrophages apparently remains the same. Th e results based on the incorporation of [H-3]phenyl alanine and suppor ted by the binding of glycosylated liposomes to both infected and non- infected macrophages suggest that protein synthesis, in general, is su ppressed in L. donovani-infected macrophages thus affecting also manno se/glucose receptor protein synthesis, resulting in fewer receptors on the macrophage surface.