The Non-Specific Binding of Immunoglobulins to Silicone Implant Materials: The Lack of a Detectable Silicone Specific Antibody

Abstract

Recent studies have suggested that anti-silicone antibodies develop in patients implanted with silicone materials. The majority of these studies have utilized enzyme-linked immunosorbent assay (ELISA) methodology with a silicone material substrate as a means to detect the presence of the anti-silicone antibody. The current studies were undertaken to determine whether the binding of IgG to a silicone substrate was consistent with an antigen-specific antibody interaction or the result of non-specific hydrophobic interactions. While significant differences were detected in serum from silicone antibody “positive” and “negative’’ patients when the ELISA was conducted using a phosphate buffered saline (PBS)-0.05% Tween 20 (Tween) blocking system, the difference in the responses was attenuated when protein blocking systems were used or when incubation times were decreased. Furthermore, ELISA studies, using purified mouse and human IgG, demonstrated a concentration-dependent binding of IgG to silicone elastomer substrate which was also attenuated when a protein blocking system was used in lieu of Tween. In controlled animals studies in which female B6C3F1 mice were implanted with silicone gel or silicone elastomer for 180 days, no difference was observed between the implanted animals and the PBS control animals with respect to binding of IgG to the silicone substrate. Similar studies in female Fischer 344 rats implanted with silicone gel for 84 days also failed to demonstrate the presence of anti-silicone antibody. Collectively, the results suggest that the binding of IgG to silicone implant materials is non-specific in nature, consistent with the well-recognized interactions between hydrophobic molecules (IgGs) and hydrophobic surfaces (silicones) in an aqueous-based system.