Cr(VI) induced suppression of Drosophila cellular immune response: protection by sod overexpression. Pragya Prakash^1*, Arvind Shukla¹, M.Z. Abdin², Debapratim Kar Chowdhuri¹. 1) Embryotoxicology, CSIR-Indian Institute of Toxicology Research, Lucknow, Uttar Pradesh, India; 2) Department of Biotechnology, Jamia Hamdard, Hamdard Nagar, New Delhi 110 062.

   The immune system is the first line of defense mechanism in all metazoans. A number of anthropogenic activities release thousands of chemicals into the environment which exert adverse effects on immune system. In the present study, in vivo effect of Cr(VI) on Drosophila cellular immune response was evaluated and subsequent protection by sod overexpression was examined. The immunosuppressive potential of Cr(VI) was demonstrated by a significant reduction in total hemocyte count in the exposed organism. A significant increase in annexin V-FITC positive cells, DEVDase activity and Reactive Oxygen Species (ROS) generation along with deterioration of antioxidant defense system in hemocytes of the exposed organism was also observed. This indicates that Cr(VI) exposure generates ROS mediated oxidative stress in the hemocytes. Further, Cr(VI) induced immunosuppressive effect was shown to be significantly reduced by the overexpression of one of the antioxidant genes, sod, in Drosophila hemocytes. This study demonstrates the applicability of Drosophila melanogaster to examine the possible immunotoxic effects of environmental chemicals along with its amelioration by sod overexpression. Overall, it has been suggested that overexpression of sod benefits the organism from Cr(VI) induced immunosuppressive effect on cellular immune response.