Tumor promoters differ in their ability to stimulate superoxide anion radical production by murine peritoneal exudate cells following in vivo administration

Abstract

The production of superoxide anion radicals by murine peritoneal exudate cells (PECs) following intraperitoneal (i.p.) injection of mouse skin tumor promoters was assessed in vitro by the reduction of nitroblue tetrazolium (NBT). Phorbol-12-myristate-13-acetate (PMA) or mezerein when administered i.p. to CD-1 female mice at a dose of 0.1 microgram caused an inflammatory response in the peritoneal cavity. PMA (0.1 microgram) also caused an increase in the number of PEC reducing NBT, i.e. formazan-positive PECs (20% positive cells) as compared to vehicle control from 15 min through 2 h following i.p. administration to unmanipulated mice. In the same system, dose-response studies demonstrated that 4-O-methyl-phorbol myristate acetate (4-O-Me-PMA) and mezerein were approximately 50 times less active than PMA, while phorbol dibutyrate (PDB), phorbol diacetate (PDA), phorbol and the calcium ionophore A23187 did not cause an increase in the number of formazan-positive PECs at the doses used. When the same compounds (0.1 microgram) were administered to mice which had been pretreated i.p. with thioglycollate 6 days prior to the experiment, PMA, PDB, 4-O-Me-PMA, mezerein and A23187 all caused an increase in the number of formazan-positive PECs 2 h after treatment. The PEC which reduced NBT in response to tumor promoters were predominantly adherent and esterase positive cells, suggesting they were macrophages. These results indicate that in vivo administration of tumor promoters results in the production of superoxide anion radicals by murine peritoneal macrophages and that the physiological state of the macrophages is important in the response to tumor promoters.(ABSTRACT TRUNCATED AT 250 WORDS)