Enumeration of macrophage carbohydrates in protein-deficient rats: relation to cell surface properties

In order to study the effect of protein malnutrition on macrophage glycoproteins the carbohydrate composition of peritoneal macrophages from protein-deficient rats has been studied by paper chromatography and HPLC. The results show that the carbohydrate content of resident cells recovered from protein-deficient group was significantly greater than control and decreased on prolonged incubation. In the protein-deficient samples there was a significant decrease in the content of galactose, fucose and galactosamine known to be binding to specific ligands and increase in glucose and mannosamine. In both control and deficient groups, thioglycollate (TG) elicitation resulted in higher total sialic acid content. Prolonged incubation (18 hr) caused an elevation of sialic acid levels in the resident cells, whereas a drastic reduction was observed in the TG elicited cells. In the protein-fed (20%) group, the cell surface sialic acid which contributes to the negative charge of the cells, reduced significantly on culturing the TG cells but not the resident cells. In the protein-deficient group, this effect was seen in the resident cells also; in the TG cells the cell surface sialic acid was significantly low at the isolation stage suggesting that these cells had become comparatively more positively charged in vivo itself. This observed reduction could be correlated to the enhanced sialidase levels in these cells. These protein deficiency related changes in the carbohydrate composition of macrophages could lead to modification of their receptor activity and charge related functions.