In vivo cytokine production and resistance to infection after acute exposure to 3,4-dichloropropionaniline.

3,4-Dichloropropionaniline (propanil) is an extensively used postemergent herbicide that has been shown to produce toxic and immunotoxic effects. The present report examined if acute exposure to propanil altered in vitro or in vivo cytokine production in response to antigenic stimulation. Studies to determine resistance to infection by the intracellular bacterium Listeria monocytogenes after exposure to propanil were also conducted. Our experiments demonstrate that in vivo exposure to propanil during bacterial infection reduced the subsequent in vitro production of interferon-gamma (IFN-gamma) by splenocytes and liver nonparenchymal cells in response to antigenic and mitogenic stimulation. Additional experiments examined the production of cytokines in vivo after propanil exposure alone or combined propanil exposure and L. monocytogenes infection. It was found that the endogenous levels of cytokines in the liver, spleen, and blood were similar in control and propanil-treated mice. The levels of cytokines were also similar in control and exposed mice that were infected with L. monocytogenes. Initial resistance to the infection was not affected by exposure to propanil. These results demonstrate that in vivo exposure to propanil during a bacterial infection suppresses the subsequent in vitro production of cytokines but that the endogenous levels are not affected during the initial stages of infection.