Abstract:

Both antibodies and complement components are essential for successful phagocytosis of many virulent microorganisms (1,2). Although the mechanisms by which opsonins promote particle uptake are not fully understood, it has been suggested that both electrostatic and hydrophobic forces act in concert with specific receptors for Fc and C3b to facilitate interiorization of particles (2,3). In the case of group A streptococci, opsonization by immunoglobulins abolishes the anti-phagocytic properties of the M-antigen (4,5). Since one mechanism by which opsonins may act is to decrease repulsion forces between negative charges present on the surface of the particle and phagocyte, cationic ligands may function as effective opsonins (6–11). In addition, cationic substances may participate in bacteriolysis. We recently suggested (11) that the breakdown of bacterial cells following phagocytosis is mediated indirectly by leukocyte cationic proteins and phospholipases which activate autolytic enzymes and not by lysosomal enzymes directly.