Adjuvancy effect of different types of silicone gel

Women with silicone gel-filled breast implants (SBIs) are likely to be at a slightly higher risk of developing an autoimmune-like syndrome. This risk, although small, may be associated with the immunological adjuvancy property of the silicone gel. However, not all silicone gels are chemically formulated exactly the same and their adjuvancy behavior may vary. This study compared, in rats, the adjuvant effect of three different lots of silicone gel using ovalbumin (OVA) as the test antigen. Test bleeds were taken at 21, 48, 62, and 84 days post immunization and the rat sera were analyzed for anti-OVA antibodies by enzyme linked immunosorbent assay (ELISA). A delayed type hypersensitivity (DTH) test was performed on all the treated rats beginning at 14 post-immunization days. The results showed that silicone gel #3 (McGhan lot #S0400488) produced the highest mean anti-OVA antibody titer followed by silicone gel #1 (DC lot #HH019581) and silicone gel #2 (McGhan lot #DP9339). The DTH results showed that rats treated with silicone gel #1 and #3 had a clear positive response, whereas silicone gel #2 caused only a minimal response. These results demonstrate the immunological adjuvancy difference among three types of silicone gel. The chemical composition of each of these silicone gels, that would help explain these results, is yet to be determined.