Abstract:

Voluminous literature exists today on the involvement of cationic polyelectrolytes (CPs) in host and parasite interrelationships. It has been shown that CPs of neutrophil (1-14), eosinophil (15, 16), macrophage (17), and platelet (18) origins function as distinct microbicidal agents. These probably constitute a "secondary" defense line supplementary to the main oxygen-dependent microbicidal systems of "professional" phagocytes. CPs have, however, also been implicated as modulators of blood clotting (19) and fibrinolysis (20), as a permeability-enhancing factors (21-23), in mast cell degranulation and in histamine release (24), as pyrogenic agents (25), as enhancers of complementmediated lysis (26), as modulators of PMN adherence (27-29) and chemotaxis (30-34), and as modulators of endocytosis (35-45) to list only several of the properties ascribed to these agents. Since the effects of CPs probably involve the interaction, through electrostatic forces, with negatively charged sites on target cells (36), it is plausible that the complex polyelectrolytic milieu found in infectious and inflammatory sites might function to modulate and regulate several important interactions of the host with invaders (46-48). Although CPs are primarily recognized for their distinct killing properties (10-13), recent studies have suggested that CPs might also be involved in a variety of additional biological, biochemical, and immunopathological phenomena which are seldom discussed in the general context of host and parasite interrelationships. The present review deals primarily with the possible involvement of CPs (1) in endocytosis and in cell adherence, (2) as activators of the respiratory burst in "professional" phagocytes, (3) as activators of the autolytic wall enzymes in certain microbial species and its relation to bacteriolysis and to the pathogenesis of chronic inflammation induced by bacterial cell walls, and (4) as agents capable of modulating the pathogenicity of immune complexes. It was felt that a discussion of these "other" properties of CPs is timely as it may shed a new light on the role of surface charge in cell-to-cell interactions as seen in inflammatory and infectious sites.