Immunological studies of malathion as an example of insecticides

This study was carried out to determine the immunotoxic effect of malathion insecticide on female albinorats. 500 albino rats were classified according to the duration of expasure to malathion into 3 groups. Each group was subdivided into two groups; A and B. Groups IA, IIA, and III A were control groups receiving distilled water for 30, 60 and 90 days respectively. Whereas groups IB, IIB, and IIIB were receiving malathion in a single dose of 137.5 mg/kg daily, orally for 30, 60, and 90 days respectively. Evaluation of the immunotoxic effects of malathion had been determined by measuring selected parameters. Measurement of total and differential WBC count by automated cell counter and leishman stained blood films. Assessment of structural integrity of spleen, thymus and adrenals by measuring organ weight to total body weight ratio. Humoral immunity was assessed by measuring the concentration of serum IgG, IgM, and polyvalent Ig, [IgG, IgM and IgA] by sandwich EIA. Cell mediated immunity was assessed by measuring the concentrations of serum IL-2, IL-10 and IFN-gamma by sandwich EIA, and by measuring the capacity of T-lymphocytes to proliferate in response to PHA stimulation by Beta cell counter. There was a decrease in total leukocytic count, lymphocytes percentage, and spleen and thymus weight ratios. While there was an increase in adrenals weight ratio. These changes were significant with increased duration of exposure to malathion. Serum IgG, IgM and polyvalent Ig were decreased in the 3 groups of rats, compared with the control groups and the decrease was more significant with increased duration of exposure. Serum IL-2, IL-10 and IFN- gamma were also decreased in the 3 groups compared is the control groups and the decrease was more significant with increased duration of exposure. The percentage of T-cell proliferation in response PHA stimulation was decreased in the 3 groups of rats compared to the control groups. Malathion induced immunosuppressive effects on albino rats involve nonspecific immune response and both humoral and cell mediated immunorespones