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Parathion-induced suppression of humoral immunity in inbred mice
Abstract:
Numbers of IgM plaque-forming cells (PFC) were reduced by 65% in C57Bl/6 mice given parathion 2 days after immunization with sheep red blood cells (SRBC). The immunosuppressive dose (16 mg/kg, p.o.) caused signs of cholinergic poisoning and 20% mortality. Survivors appeared to have recovered fully from the cholinergic crisis at the time of immunologic assay. However, these animals had reduced tissue cholinesterase (ChE) activities and decreased numbers of nucleated spleen cells. Immunosuppression was apparent on day 4 but not on day 3 or days 5-8 of the primary IgM response. Reduction of serum hemagglutinin titers coincided with reduction of the number of splenic PFC. A lower dose of insecticide (4 mg/kg, p.o.) did not produce signs of poisoning and was not immunosuppressive. The number of 8-day IgG PFC was reduced by 45% when parathion (16 mg/kg, p.o.) was given 6 days after immunization, but not when parathion was given 2 days after immunization. The data suggest that cholinergic stimulation and/or the associated toxic chemical stress may be involved in parathion-induced immunosuppression.
Insights
Parathion insecticide exposure significantly reduced immune cell activity in mice, impacting both IgM and IgG responses. This immunosuppression was linked to cholinergic poisoning and reduced cholinesterase activity.
Area of Science:
- Immunology
- Toxicology
- Neuroscience
Background:
- Organophosphate pesticides like parathion are widely used.
- Exposure can lead to cholinergic crisis and potential health effects.
- Immunological impacts of pesticide exposure require further investigation.
Purpose of the Study:
- To investigate the immunosuppressive effects of parathion on the primary antibody response in mice.
- To determine the relationship between parathion dosage, cholinergic toxicity, and immune cell function.
Main Methods:
- C57Bl/6 mice were immunized with sheep red blood cells (SRBC).
- Parathion was administered orally at different doses (16 mg/kg and 4 mg/kg) at varying time points post-immunization.
- Immune responses were assessed by quantifying IgM and IgG plaque-forming cells (PFC) and serum hemagglutinin titers.
- Cholinesterase (ChE) activity and spleen cell counts were measured.
Main Results:
- A high dose of parathion (16 mg/kg) administered 2 days post-immunization reduced IgM PFC by 65% and caused cholinergic poisoning with 20% mortality.
- Survivors showed reduced ChE activity and fewer nucleated spleen cells, with immunosuppression evident on day 4 of the IgM response.
- A lower dose (4 mg/kg) was not immunosuppressive.
- Parathion given 6 days post-immunization reduced IgG PFC by 45%, but not when given 2 days post-immunization.
Conclusions:
- Parathion exposure can suppress both primary IgM and secondary IgG antibody responses in mice.
- The timing of exposure relative to immunization influences the degree of immunosuppression.
- Cholinergic stimulation and toxic chemical stress are implicated in parathion-induced immunosuppression.