Macrophage functional activities versus cellular parameters upon sublethal pesticide exposure in mice

The toxicity of selected organochlorine, organophosphate, and carbamate pesticides on the functions and cellular parameters of peritoneal macrophages was examined in inbred C57Bl/6 mice. Effects of single, sublethal pesticide exposure on macrophages were determined by analysis of the cell viability, cell adherence capacity, generation of superoxide anion (O2-), antigen processing, phagocytosis of Salmonella typhimurium, and resistance to in vitro virus-induced cytopathic effects (cpe) after infection with mouse hepatitis virus 3 (MHV3). Most of the studies were done for the organochlorine pesticide dieldrin, which inhibited several macrophage functions, such as phagocytosis of S. typhimurium, release of the single processed protein antigen avidin, and resistance to MHV3 virus-induced cpe. The virus-induced cytolysis in macrophage cultures was significantly increased after in vivo exposure to single sublethal doses of other selected pesticides, such as guthion, carbofuran, sevin, and matacil. However, none of the selected pesticides, used in sublethal (0.4 less than or equal to LD50 less than or equal to 0.6) doses appeared to be a factor impairing the O2- -generating system in chemically elicited or immunologically activated peritoneal macrophages. In conclusion, sublethal pesticide exposure can induce a significant impairement of several macrophage functions, such as phagocytosis, antigen processing, and resistance to virus-induced cytolysis. Inhibition of the O2- -generating system by sublethal pesticide exposure, however, can be excluded as a mechanism of potential suppressory action of these pesticides on antiviral and antibacterial host defence systems in which macrophages play a primary role.