Chemiluminescence and superoxide generation by leukocytes stimulated by polyelectrolyte-opsonized bacteria

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Abstract
Human blood leukocytes generate intense luminol-dependent chemiluminescence (LDCL) following stimulation by streptococci and by Gram negative rods which had been preopsonized by cationic polyelectrolytes (histone, poly L-arginine-PARG, poly L-histidine-PHSTD). Streptococci but not Gram negative rods or hyaluronic acid-rich streptococci (group C) also induced intense LDCL following opsonization with the anionic polyelectrolytes-dextran sulfate or polyanethole sulfonate (liquoid) suggesting that the outer surfaces of different bacteria bound anionic polyelectrolytes to different extents. Both normal and immune serum, synovial fluids and pooled human saliva inhibited the LDCL responses induced by streptococci preopsonized with poly cations. On the other hand, bacteria which had been first preopsonized by the various body fluids and then subjected to a second opsonization by cationic ligands (“sandwiches”), induced a very intense LDCL response in leukocytes. Streptococci which had been preopsonized by PARG, histone or by PHSTD also triggered superoxide generation by blood leukocytes, which was markedly enhanced by a series of cytochalasins. PHSTD alone induced the formation of very large amounts of superoxide. Paradoxically, the same concentrations of cytochalasins B or C which markedly boosted the generation of superoxide following stimulation of leukocytes with soluble or particulate ligands, had a strong inhibitory effect on the generation of LDCL. On the other hand cycochalasins failed to inhibit LDCL which had been induced by phorbol myristate acetate (PMA). Peritoneal macrophages which had been harvested from C. parvum-stimulated mice, generated more LDCL and superoxide following stimulation by PARG than macrophages obtained from proteose peptone-stimulated mice. Macrophages which had been activated either by proteose peptone or by C. parvum and cultivated for 2 hours on teflon surfaces, generated much more LDCL than macrophages which had been cultivated for 24 hours on teflon surfaces. Both cationic and anionic polyelectrolytes mimic the effects of antibodies as activators of the oxygen burst in blood leukocytes and in macrophages. Such polyelectrolytes can serve as models to further study leukocyte-bacteria interactions in infectious and inflammatory sites.