Mercury exposure, malaria, and serum antinuclear/antinucleolar antibodies in Amazon populations in Brazil: a cross-sectional study.
BACKGROUND
Mercury is an immunotoxic metal that induces autoimmune disease in rodents. Highly susceptible mouse strains such as SJL/N, A.SW, B10.S (H-2s) develop multiple autoimmune manifestations after exposure to inorganic mercury, including lymphoproliferation, elevated levels of autoantibodies, overproduction of IgG and IgE, and circulating immune complexes in kidney and vasculature. A few studies have examined relationships between mercury exposures and adverse immunological reactions in humans, but there is little evidence of mercury-associated autoimmunity in humans.


METHODS
To test the immunotoxic effects of mercury in humans, we studied communities in Amazonian Brazil with well-characterized exposures to mercury. Information was collected on diet, mercury exposures, demographic data, and medical history. Antinuclear and antinucleolar autoantibodies (ANA and ANoA) were measured by indirect immunofluorescence. Anti-fibrillarin autoantibodies (AFA) were measured by immunoblotting.


RESULTS
In a gold mining site, there was a high prevalence of ANA and ANoA: 40.8% with detectable ANoA at > or =1:10 serum dilution, and 54.1% with detectable ANA (of which 15% had also detectable ANoA). In a riverine town, where the population is exposed to methylmercury by fish consumption, both prevalence and levels of autoantibodies were lower: 18% with detectable ANoA and 10.7% with detectable ANA. In a reference site with lower mercury exposures, both prevalence and levels of autoantibodies were much lower: only 2.0% detectable ANoA, and only 7.1% with detectable ANA. In the gold mining population, we also examined serum for AFA in those subjects with detectable ANoA (> or =1:10). There was no evidence for mercury induction of this autoantibody.


CONCLUSIONS
This is the first study to report immunologic changes, indicative of autoimmune dysfunction in persons exposed to mercury, which may also reflect interactions with infectious disease and other factors.
Silva
Ines A
IA
The Johns Hopkins University Bloomberg School of Public Health, 615 N, Wolfe Street, Room E6642, Baltimore, Maryland 21201, USA. imtasilva@hotmail.com
Nyland
Jennifer F
JF
Gorman
Andrew
A
Perisse
Andre
A
Ventura
Ana Maria
AM
Santos
Elizabeth C O
EC
Souza
Jose M de
JM
Burek
C L
CL
Rose
Noel R
NR
Silbergeld
Ellen K
EK
D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001938:Brazil; D003430:Cross-Sectional Studies; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005398:Fisheries; D006046:Gold; D006801:Humans; D008288:Malaria / Q000097:blood / Q000276:immunology*; D008297:Male; D008630:Mercury Poisoning / Q000097:blood / Q000276:immunology*; D008906:Mining; D016273:Occupational Exposure / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D000974:Antibodies, Antinuclear; D015415:Biomarkers; D014874:Water Pollutants, Chemical; D006046:Gold