INCORPORATION OF [H-3]URIDINE INTO RNA UNDER THE INFLUENCE OF DIELDRIN AND POLYCHLORINATED BIPHENYLS

The present study was conducted to determine the influence of two organochlorines, i.e., polychlorinated biphenyl (Aroclor 1242) and dieldrin, or RNA synthesis in elicited peritoneal macrophages. Tritiated uridine ([3H]uridine) incorporation into RNA was used as an index of RNA synthesis. RNA synthesis was depressed in macrophages incubated in the presence of dieldrin in both a time- and dose-related manner. The dieldrin-induced inhibition of RNA synthesis was further exacerbated when the macrophages were actively phagocytosing latex particles. Aroclor 1242 similarly inhibited RNA synthesis in resting macrophages; however, inhibition was not seen until a concentration exceeding 7 ppm of Aroclor 1242 was used in the incubation medium. Dieldrin-induced inhibition of RNA synthesis was observed at levels of 1 ppm. The inhibition of RNA synthesis provides a corroborative index to support the hypothesis previously advanced that the observed in vivo organochlorine-induced immune suppression may be macrophage mediated. Since the observed in vivo immune suppression was manifested in the absence of any morphological changes in the target lymphoid-macrophage tissues, a biochemical lesion, perhaps at the level of RNA synthesis, may be a site for the organochlorine-induced immunosuppression. © 1979.