Marcadores imunológicos na exposição mercurial na Região Amazônica

Abstract

Immune dysfunctions can appear by combination between genetic susceptibility and environmental factors. There are evidences, in humans exposed to total mercury (Hgt), of alterations in immune response, by Hgt induced autoantibodies. This work investigated the occurrence of Hgt-induced autoimmunity (HgtIA) among human being exposed to Hgt in the Tapajós region (Barreiras, Brasília Legal, São Luís do Tapajós), as well as in the riverines from Tocantins region (Panacauera) without exposition to Hgt. The of hair and blood samples were collected from 236 individuals during June of 2004 to December of 2006, in which the total mercury in hair was determined by atomic absorption spectrophotometer, and in the serum, autoantibodies were analyzed by indirect immunofluorescence microscopy, using human epithelial cells (HEp-2) as substrate. The highest Hgtotal levels was found in São Luís do Tapajós (11.24 ± 2.23 μg/g), following for Brasília Legal (10.00 ± 0.99) and Barreiras (8.64 ± 1.13), and the lowest were found in Panacauera (2.98 ± 0.20). When considering the variable sex, association with the levels of Hgtotal in hair was observed only in Brasília Legal. Regarding mercury exposure, the autoantibodies in serum was more frequent in riverine of the Tapajós (79.65%) than in the control group (31.25%). Most of the autoantibodies patterns identified by immunofluorescence were: mixed (50.96%), nuclear (31.21%), nucleolar (14.65%) and mitotic apparatus/cytoplasmatic (3.18%). The mixed and nuclear autoantibodies patterns were observed in exposed communities (p<0.01). In addition, various widely recognized autoimmune disease specific autoantibodies were also found, which occurred more frequently as following: NuMa1, PM/Scl, Ssa-Ro, rRNP/Sm, golgi/Ssa/Ro, PCNA, rRNP, Ku, besides other autoantibodies without defined specificity. The intensity of immunofluorescence was more reactive in riverine of the Tapajós (p<0.0001). Analysis by regression logistics multiple indicated that the risk of autoantibodies present in serum was twice higher in riverines exposed to mercury (>10μg/g) with age group above 50 years (p>0.01). Finally, additional studies are indispensable to confirm the specificity of these autoantibodies associated with the mercurial exposure, as well as to elucidate the mechanisms immunotoxicologicals of action of the mercury on the human immune system.