| Abstract: | When a streptococcal preparation, OK-432, was administered intraperitoneally to patients with malignant ascites, the number of neutrophils with cytotoxic activity against tumor cells was increased in the peritoneal cavity immediately after the OK-432 injection. In order to investigate the underlying mechanisms of such neutrophil accumulation, a possible neutrophil chemotactic activity in ascitic fluid was assayed by a modified Boyden method. The chemotactic activity for neutrophils was found significantly higher 6 hr after the OK-432 injection. OK-432 along had no direct chemotactic activity for neutrophils. The chemotactic activity was generated in vitro when ascitic fluid from patients without OK-432 treatment was incubated with OK-432 for 30 min at 37 degrees C. However, preheating of the fluid at 56 degrees C for 30 min or the addition of EDTA to the fluid resulted in the failure of generation of the chemotactic activity after the incubation with OK-432. The addition of EGTA did not show a significant effect. The chemotactic activity in ascitic fluid was found near cytochrome c marker (MW 12,400 D), when fractionated by Sephadex G-200 gel chromatography. The chemotactic activity was heat stable, nondialyzable, and neutralized completely with anti-human complement C5 antibodies. These results suggest that C5a generated via the alternative pathway activated by OK-432 may be responsible for the infiltration of killer neutrophils in the peritoneal cavity in patients with malignant ascites when they are treated by the intraperitoneal injection of OK-432. |
