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Effect of chlorpyrifos on immune function in rats
B R Blakley1, M J Yole, P Brousseau
1Department of Veterinary Physiological Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada.
Veterinary and Human Toxicology
|June 1, 1999
Summary
Chlorpyrifos exposure in rats impaired T-lymphocyte function and altered lymphocyte subpopulations, indicating immune system alterations. This study highlights potential immunotoxic effects of this common pesticide.
Area of Science:
- Immunotoxicology
- Environmental Health
- Pesticide Toxicology
Background:
- Chlorpyrifos is a widely used organophosphate insecticide.
- Understanding its impact on the immune system is crucial for public health.
- Previous research suggests potential immunomodulatory effects.
Purpose of the Study:
- To evaluate the effects of a commercial chlorpyrifos formulation on specific immune functions in male Fisher 344 rats.
- To investigate chlorpyrifos-induced changes in T-lymphocyte and B-lymphocyte responses.
- To assess alterations in humoral immunity, macrophage activity, and lymphocyte subpopulations.
Main Methods:
- Male Fisher 344 rats were administered chlorpyrifos (5.0 mg/kg) via oral gavage twice weekly for 28 days.
- Assessed body weight, organ/body weight ratios, T-lymphocyte and B-lymphocyte blastogenesis.
- Measured humoral immunity (anti-sheep red blood cell response), macrophage phagocytosis, and cell surface antigen expression (CD5+, CD8+).
Main Results:
- Chlorpyrifos did not affect body weight or organ weights.
- Impaired T-lymphocyte blastogenesis (concanavalin A, phytohemagglutinin) but not B-lymphocyte blastogenesis.
- Reduced humoral immunity when expressed per spleen cell count, associated with a 91% increase in splenic lymphocytes.
- No effect on macrophage phagocytosis, but increased CD5+ and CD8+ T-lymphocyte percentages.
Conclusions:
- Chlorpyrifos induces significant alterations in the rat immune system.
- Specifically, it impairs T-lymphocyte proliferation and modifies lymphocyte subpopulations.
- These findings suggest chlorpyrifos possesses immunotoxic properties affecting cellular immunity.
