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Key words: autoimmune disease, breast implants, silicone gel
Autoimmune diseases have been reported in women with silicone breast implants. The presence of autoantibodies in some of the women, as well as studies in experimental animals, suggest that silicone may have adverse effects on the immune system. The goal of this project is to determine if antibodies can be raised to homologous connective tissue proteins when rats are immunized with protein antigens mixed with silicone gel from a breast implant. Four different antigens were used: (1) human thyroglobulin (as a foreign antigen used as a positive control), (2) rat collagen (type I), (3) rat collagen (type II), and (4) rat fibronectin. Two strains of rats were used: a normal Sprague-Dawley (SD) rat and an autoimmune-susceptible Dark-Agouti (DA) rat.
Our data demonstrate that statistically significant levels of autoantibodies against collagen are seen in the autoimmune-susceptible DA rats immunized with collagen-plus-silicone gel/oil from 24 to 53 weeks after immunization. No significant levels of autoantibodies against Type 1 collagen were detected in normal SD rats immunized with collagen+ silicone gel/oil throughout the duration of the experiments. However, when SD rats were immunized with silicone oil alone, significant levels of autoantibodies against Type 1 rat collagen were detected.
From these data we can conclude that silicone gel/oil (administered with antigen in autoimmune susceptible rats and without antigen in normal rats) can promote autoantibody production against homologous antigen. This effect may be strain-dependent, suggesting that genetic predisposition may be a factor. Unlike routine immunization against foreign substances, it takes several months to detect the presence of autoantibodies and antibody levels are low. Silicone gel, like other adjuvants, can cause gross immunopathology, and can migrate as well as remain at the site of implantation for at least one year. We have demonstrated, by confocal spectroscopic immunodetection, that collagen formation can occur at these sites. Tumor formation can occur, and may be dependent upon genetic predisposition, although its relation to the presence of silicone is unclear. We are currently investigating the detection of silicone gel in rat tissues using a fluorescent stain. This simple technique would be useful for biopsy tissues which might contain silicone leaked from implants. [PreME, PostMS, ProA]