4.5. Cell mediated immune response
The significantly decreased skin fold thickness (SFT) in the As exposed kids as compared to the control group indicated poor reactivity of host against the mitogen by CMI response, which may be due to toxic effects of As on lymphoid organs.Most of the available reports have also indicated an adverse effect of As on CMI response in the animals. Similarly, cellular immunity was adversely affected by inorganic arsenicals as exhibited by inhibition of DNA synthesis of lymphocytes (Mengand Meng, 2000).The mechanism of As induced immunosuppression is not completely understood. Chronic exposure to As may affec tlymphocyte, monocyte and macrophage activity resulting in immuno-suppression in many mammals (Sakurai et al., 2006).Arsenic also induces apoptosis in various cell systems leading to a defective cell mediated immunity and decrease percentageof T cell and T helper cell sub populations in peripheral nuclear cells (Yu et al., 2002). It has also been suggested that As itself alters cellular interactions by binding with sulfhydril groups of cell membrane (Goyer and Clarkson, 2008).It was further observed that vitamin E could largely ameliorate the adverse effects of As on CMI response as SFT in groupT3 was similar to control group (T1).