IMMUNOHISTOCHEMICAL DEMONSTRATION OF CARCINOGEN-DNA ADDUCTS IN TISSUES OF RATS GIVEN 2-AMINO-1-METHYL-6-PHENYLIMIDAZO[4,5-B]PYRIDINE (PHIP)- DETECTION IN PARAFFIN-EMBEDDED SECTIONS AND TISSUE DISTRIBUTION

A polyclonal antibody against 2-amino-1-methyl-6-phenylimidazo[4,5-b]p yridine (PhIP)-DNA adducts was raised for their immunohistochemical de monstration in paraffin-embedded sections. Specificity of this antibod y was confirmed by competitive ELISA, Positive signals were immunohist ochemically detected in acetone-fixed but not in formalin- or ethanol- fixed sections from F344 rats treated by gavage with a single dose of PhIP at 37.5-300 mg/kg and killed at 1, 2, and 7 days thereafter. Dose -dependent positive staining was observed in almost all organs of both sexes, including the colon, prostate, and mammary gland but largely i ndependent of the tumor response. Repair activity, judged by disappear ance of adducts with time, differed according to the organ or cell typ e. One exception was hepatocytes, the liver incidentally being a nonta rget organ. The results suggest that the generated antibody is applica ble for detection of cells targeted by PhIP in paraffin-embedded secti ons and also for the investigation of the mechanisms of PhIP-carcinoge nesis.