Abstract:

Introduction Cationic polyelectrolytes play important roles in many biological systems. Histones [20] and cationic proteins of lysosomal origin [8, 18, 24, 25, 28, 33, 36, 37], both rich in arginine, and synthetic poly a-amino acids [3, 4, 5, 6, 23, 30] have been shown to be bactericidal and cytotoxic to a variety of bacteria and mammalian cells. In addition, these compounds modulate blood coagulation [30] and fibrinolysis [10]; agglutinate bacteria and mammalian cells [30]; modulate chemotaxis [16]; enhance adherence of mammalian cells to surfaces [26]; function as opsonins for phagocytosis by both "professional" and "nonprofessional" cells [3,5,6,17,27,28,34]; activate autolytic cell wall enzymes of Staphylococci [15]; and block Fe receptors for IgG upon certain group A Streptococci [14]. More recent studies have shown that histone-opsonized bacteria induced intense Iuminot- dependent chemiluminescence (LDCL) in human polymorphonuclear leukocytes (PMNs) and mouse peritoneal macrophages [In Furthermore, poly-i.-arginine collaborated with mixtures of lectins, calcium ionophore and the chemotactic peptide formyl-methionyl-Ieucyl-phenylalanine to induce synergistic LDCL and superoxide production in human PMNs [12,13]. Thus, arginine-rich polyelectrolytes appear to participate in many cellular functions related to host defenses against infection, presumably by mechanisms involving electrostatic interactions and ligand- receptor coupling phenomena. The objective of this present study was to investigate the possibility that arginine- rich polycations might facilitate the introduction of a variety of agents into eukaryotic cells. For this purpose, we have studied phagocytosis by Entamoeba histolytica of Candida albicans, and by Acanthamoeba palestinensis of Mycobacterium marinum.