Immunotoxicity in mice induced by short-term exposure to methoxychlor, parathion, or piperonyl butoxide

Exposure to environmental agents can compromise numerous immunological functions. Immunotoxicology focuses on the evaluation of the potential adverse effects of xenobiotics on immune mechanisms that can lead to harmful changes in host responses such as: increased susceptibility to infectious diseases and tumorigenesis; the induction of hypersensitivity reactions; or an increased incidence of autoimmune disease. In order to assess the immunosuppressive response to short-term exposure to some commonly used pesticides, the studies here focused on the response of mice after exposures to the organochlorine pesticide methoxychlor, the organophosphorus pesticide parathion, or the agricultural insecticide synergist piperonyl butoxide. In these studies, 7-week-old mice were orally administered (by gavage) methoxychlor, parathion, or piperonyl butoxide daily for five consecutive days. On Day 2, all mice in each group were immunized with sheep red blood cells (SRBC), and their SRBC-specific IgM responses were subsequently assessed. In addition, levels of B-cells in the spleen of each mouse were also analyzed via surface antigen expression. The results of these studies indicated that treatments with these various pesticides induced marked decreases in the production of SRBC-specific IgM antibodies as well as in the expression of surface antigens in IgM- and germinal center-positive B-cells. Based on these outcomes, it is concluded that the short-term exposure protocol was able to detect potential immunosuppressive responses to methoxychlor, parathion, and piperonyl butoxide in situ, and, as a result, may be useful for detecting other environmental chemical-related immunotoxicities.