Organochlorine pesticides disrupt T helper cell regulation and reduce IL-2 and IFN-γ favoring infection and production of autoantibodies among pemphigus patients

Abstract

The list of environmental factors that trigger autoimmune diseases in genetically susceptible individuals has grown in the recent years and is far from complete. The possible intervention of the environment in triggering these diseases is ever more perceived by the clinicians. This study investigated the effect of environmental factors like organochlorine pesticides (OCPs) on proportions of different T lymphocyte subsets and their cytokine secretion in-vitro among pemphigus patients, before and after specific immunosuppressive therapy. Higher levels of OCPs like β-HCH (isoform of hexachlorohexane), α-endosulfan (a form of endosulfan) and p,p΄-DDE (a metabolite of o,p'-dichlorodiphenyltrichloroethane) were observed in the blood of pemphigus patients as compared to healthy controls. HCH and DDT exposure caused specific reduction in CD8⁺CD45RA⁺ and CD4⁺CD25⁺ T lymphocyte subpopulations in these patient PBMCs. A strong reduction in Th1 (IL-2 and IFN-γ) cytokines upon exposure to these OCPs in-vitro was also observed. These findings indicate that HCH and DDT have a significant impact on Th1 lymphocytes. Impaired production of these cytokines might favor infections and production of autoantibodies. We therefore speculate that the systemic absorption of the pesticide after the topical contact may be one of the factors triggering the immunological mechanism among pemphigus patients.

Keywords: Autoimmunity; Cytokines; Immunosuppressive therapy; Organochlorine pesticides; T lymphocytes.