[Antitumor effect of intraperitoneal administration of a streptococcal preparation, OK-432, in carcinomatous peritonitis. I. Experimental study in the rat].
The effect of intraperitoneal (ip) OK-432 administration and its mechanism were investigated with experimental tumor of rats.


METHODS
4 week-old female SD rats (Slc/SD, closed colony). Tumor: An ascitic tumor, produced by intraperitoneal inoculation of strain cells. These have been established from MRMT-1, which originally was induced by 3-methyl cholanthrene administration. Experimental study: On day 4 or 6 of ip inoculation of 1 x 10(6) tumor cells, 50 KE/kg of OK-432 was administered intraperitoneally and cells were daily examined microscopically. Morphological changes around tumor cells were investigated with Papanicolaou-stained preparations. Following results were obtained: A marked increase in neutrophils was noted in ascitis at 24 hours after ip administration of OK-432; macrophages and lymphocytes appearing later than neutrophils. A subsequent decrease in neutrophils was accompanied by gradual increase in tumor cells. When OK-432 was administered intraperitoneally on day 4 of ip inoculation of tumor cells, aggregation of neutrophils around tumor cells was observed on day 6, and rosette formations around tumor cells with 76 to 10 neutrophils were noted on days 7 and 8. Subsequently tumor cells forming centers of rosettes were found to be destroyed and disappeared. On days 10 to 12, regrowth of tumor cells within incomplete rosette formation was found in ascites. The above reactions were not remarkable, when OK-432 was administered intraperitoneally on day 6 of ip inoculation of tumor cells, and were never observed in untreated cases. These results indicated that cytotoxic effects of ip administration of OK-432 were displayed mainly by rosette formation with neutrophilic cells.
D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000818:Animals; D001688:Biological Products / Q000008:administration & dosage*; D005260:Female; D009374:Neoplasms, Experimental / Q000628:therapy; D010529:Peritoneal Cavity; D010534:Peritoneal Neoplasms / Q000628:therapy*; D010538:Peritonitis / Q000628:therapy*; D010844:Picibanil / Q000008:administration & dosage*; D051381:Rats
D000276:Adjuvants, Immunologic; D001688:Biological Products; D010844:Picibanil