1Department of Veterinary Pathology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar-125004, Haryana
2Regional Research Centre on Foot and Mouth Disease, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar-125004, Haryana
*Email: deepikalather@yahoo.co.in
Online published on 19 December, 2013.
One hundred and ten broiler chicks at the age of 14 days were divided randomly into three groups viz. group A, B and C containing 40, 40 and 30 chicks, respectively. All the birds of group A and B were given 1.5 and 0.75 mg chlorpyrifos/kg bwt, respectively, orally. The group C was kept as control. Cell mediated immune response in chlorpyrifos intoxicated chicken was assessed by mitogen induced lymphoproliferative assay and phenotypic expression of avCD4+ and avCD8+ T-lymphocyte subpopulation by indirect immunoperoxidase technique. Histopathological studies of different immunological organs was undertaken to substantiate the results of cell mediated immune response in chlorpyrifos toxicity. Mitogen (PHA) driven lymphocytes proliferation response was significantly lower in the groups A and B as compared to control group. These results indicate that chlorpyrifos intoxication suppressed the cell mediated immune response in chickens. Mean absolute avCD4+ T-lymphocyte count was lower in group Aas compared to control group throughout the experiment. Mean absolute avCD8+ T-lymphocyte count was also found to be significantly decreased in group A as compared to group B and C. This may be attributed to immunosuppressive effect of chlorpyrifos intoxication on cell mediated immune response and this immunosuppression was more in group that received higher dose of CPF i.e. 1.5 mg chlorpyrifos/kg bwt as compared to the group received 0.75 mg chlorpyrifos/kg bwt. Histopathologically, chlorpyrifos intoxication in both the groups A and B revealed congestion, haemorrhages with depletion of lymphocytes and presence of multiple necrotic foci in spleen and thymus. Bursa of Fabricius revealed mild depletion of lymphocytes in bursal follicles from 14 DPCT onwards in both treated groups. The severity of histopathological lesions noticed was less in group B chicks as compared to the group A as evident by the mean gross lesion score (GLS) and mean histopathological lesion score (HLS) which was considerably higher in group Awith higher overall percent mean GLS and HLS irrespective of post infection period and organs as compared to group B. On the basis of results of the present study it is concluded that chlorpyrifos intoxication resulted in impairment of cell mediated immunity as also evident by pathological changes in various immunological organs like spleen, thymus and bursa of Fabricius.
