ADVERSE IMMUNOLOGICAL EFFECTS AND AUTOIMMUNITY INDUCED BY DENTAL AMALGAM AND ALLOY IN MICE

Dental amalgam fillings are the most important source of mercury expos ure in the general population, but their potential to cause systemic h ealth consequences is disputed. In this study, inbred mice genetically susceptible to mercury-induced immune aberrations were used to examin e whether dental amalgam may interfere with the immune system and caus e autoimmunity. Female SJL/N mice were implanted in the peritoneal cav ity with 8-100 mg silver amalgam or silver alloy for 10 weeks or 6 mon ths. Chronic hyperimmunoglobulinemia, serum IgG autoantibodies targeti ng the nucleolar protein fibrillarin, and systemic immune-complex depo sits developed in a time- and dose-dependent manner after implantation of amalgam or alloy. Splenocytes from mice implanted with amalgam or alloy showed an increased expression of class II molecules. The functi onal capacity of splenic T and B cells was affected in a dose-dependen t way: 10 weeks of low-dose and 6 months of high-dose amalgam implanta tion strongly increased mitogen-induced T and B cell proliferation, wh ereas 10 weeks of high-dose implantation decreased the proliferation. Not only mercury but also silver accumulated in the spleen and kidneys after amalgam implantation. In conclusion, dental amalgam implantatio n in a physiological body milieu causes chronic stimulation of the imm une system with induction of systemic autoimmunity in genetically sens itive mice. Implantation of silver alloy not containing mercury also i nduced autoimmunity, suggesting that other elements, especially silver , have the potential to induce autoimmunity in genetically susceptible vertebrates. Accumulation of heavy metals, from dental amalgam and ot her sources, may lower the threshold of an individual metal to elicit immunological aberrations. We hypothesize that under appropriate condi tions of genetic susceptibility and adequate body burden, heavy metal exposure from dental amalgam may contribute to immunological aberratio ns, which could lead to overt autoimmunity.