Down regulation of humoral immunity in chickens due to carbendazim

This study was planned to investigate the effect of very low dose of carbendazim on the humoral immune response in the chicken. Sixteen adult chickens, earlier vaccinated against New Castle Disease were divided in two experimental groups. Chickens of group I served as control, while group II birds were given a feed containing 200 ppm of carbendazim, which is considered no observable effect level (NOEL) dose, for a period of 6 months. The Humoral immune response was measured by the B-lymphocyte blastogenesis assay using lipopolysaccharide as mitogen and the quantitation of IgG, IgA, IgM levels by using respective antichicken conjugates, through an ELISA method. Total serum proteins, serum gamma-globulins and globulins were measured using commercially available kits. Carbendazim significantly (P< or =0.05) reduced both the B-lymphocyte proliferation and serum IgG, IgM and IgA levels, leading to decreased immunocompetence. At the end of experiment percent decrease in B-lymphocyte proliferation was 20.5% and that in serum IgG, IgM and IgA were 11.2, 22.9 and 28.8%, respectively. The percent decrease in total serum protein, serum gamma-globulins and serum globulins were 14.6, 18.5 and 9.7%, respectively. Results clearly indicated down regulation of humoral immunity by carbendazim at NOEL dose.