Impairment of Leishmania mexicana phagocytosis in peritoneal macrophages induced by Amaranthus leucocarpus lectin

The lectin from Amaranthus leucocarpus (ALL) is specific for N-acetyl-D-gal actosamine and inhibits phagocytosis of Leishmania mexicana promastigotes i n Balb/c mice peritoneal macrophages by 38%. The lipophosphoglycan (LPG) pu rified from L. mexicana inhibits penetration of promastigotes into peritone al macrophages by 31%; interestingly, treatment of macrophages with both, A LL and LPG, inhibits phagocytosis of promastigotes by 72%, confirming that ALL induces modification of the macrophage's phagocytic activity by a diffe rent route than mannose or C3b receptors. The Inhibitory effect of ALL was time-dependent. N-acetyl-D-galactosamine (GaINAc) or O-glycosidically linke d glycoproteins modified macrophage phagocytosis of Leishmania. These resul ts suggest that macrophage membrane glycoproteins, possessing constitutive GaINAc, can influence the signaling pathways used by this intracellular par asite to infect.