Streptolysin O Inhibition of Neutrophil Chemotaxis and Mobility: Nonimmune Phenomenon with Species Specificity

Abstract

The effects of streptolysin 0 (SO) (1 to 4 hemolytic units) on the mobility of neutrophilic leukocytes from humans, baboons, sheep, and rabbits were compared. After SO treatment, chemotaxis and random mobility of human neutrophils were markedly suppressed, baboon and sheep neutrophils were partially suppressed, and rabbit neutrophils were unaffected and demonstrated normal chemotaxis and mobility. The amounts of SO used in the mobility studies caused no leukocyte lysis or trypan blue uptake by human, baboon, or sheep cells, and minimal lysis or trypan blue uptake by rabbit cells. The possible involvement of immune mediators in the observed inhibition of human neutrophils was considered and excluded by the following studies. White blood cells from humans with humoral or cellular immune deficiencies responded in a manner similar to normal human cells; supernatant solutions from SO-treated human white blood cells did not contain a chemotactic suppressor; preincubation of SO with cholesterol (an inhibitor of SO hemolytic activity) caused loss of the chemotactic suppressive effect of the toxin on human leukocytes; and leukocytes from rabbits preimmunized with SO remained refractory to chemotactic suppression.Streptolysin 0 (SO), the oxygen-labile hemolysin of beta-hemolytic streptococci, is capable of degranulating and lysing white blood cells (WBC) (1,2,4) when the cells are treated with high doses of the toxin. Andersen and Van Epps (1) have shown that treatment of human WBC with low doses of SO, which were incapable of lysing the WBC or of causing any observable morphological changes, resulted in suppression of neutrophilic chemotaxis and mobility. The present study is the result of further investigations of this effect and demonstrates species specificity and the absence of immune mediators as effectors in SO chemotactic suppression.MATERIALS AND METHODS Preparation of leuk6eytes. WBC preparations were obtained from the peripheral blood of humans, baboons, sheep, and rabbits. Coagulation was prevented by heparin (10 U/ml), except in the rabbit, where the excessive amounts of heparin needed to prevent coagulation were avoided by glass bead defibrination. Defibrination of human blood with glass beads gave results similar to those where heparin was used. Red blood cells (RBC) were then sedimented for 30 min with Plasmagel (Roger Bellon Laboratories, Neuilly, France; 1 ml per 5 cm3) or with a one-third volume of pigskin gelatin (United Chemical and Organic Products, Calumet City, Ill.). In the rabbit and the sheep, pigskin gelatin proved to be a more efficient means of erythrocyte sedimentation. The supernatant solutions containing a high percentage of WBC were then decanted and centrifuged at 1,500 rpm (270 x g) for 10 min. The cells were washed twice with Hanks balanced salt solution (HBSS) and adjusted to the white cell count needed in each experiment. The human cell preparations contained approximately 65% polymorphonuclear leukocytes, 34% mononuclear cells, and a red cell-to-white cell ratio of approximately 1.4 ...

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