AbstractSilicone implants have been associated with the development of multiple organ system abnormalities, including rheumatic disorders, nervous system, pulmonary dysfunction associated with autoantibodies and abnormalities of cellular immunity. In this regards a number of case reports and series of articles have been described.We hypothesized that an immune reaction to silicone breast implants would include the host reactivity against silicone and the macromolecules within the microenvironment of the implant, and these autoantibodies may react with other tissue antigens far from the site of the implant. to test this hypothesis 520 Symptomatic women with Silicone Implants which have developed Silicone related Immunological disorders and have typically complained of breast pain, Myalgia-Arthralgia, fatigue, or generalized pain, were examined by their physician. Blood samples were obtained and examined for the presence of Silicone antibodies, Myelin Basic Protein and human serum albumin antibodies. These samples were then compared to 520 matched controls without implants. At least at the level of two standard deviation silicone specific antibodies, IgG, IgA IgM, IgE and IgG+IgA+IgM antibodies were detected above the mean of normal controls.When these antibodies were classified based on the specialty of the examining physician, the % of patients with Silicone Antibodies were varied; general practice 51.6, Rheumatology 58.7, and Plastic Surgery 83.3, which may relate to the severeness of the disease. Being that a large % of patients demonstrated very high levels of Myelin Basic Protein Antibodies, possible cross reactive antibodies were sought. However, absorption of highly positive sera for Silicone Antibodies with MBP did not change the levels of Silicone Antibodies. On the other hand, Silicone-HSA was able to reduce the antibody values significantly. This reduction in antibody levels by Silicone is the best indication for the specificity of these antibodies. Moreover when data for silicone antibodies and MBP antibodies was analyzed in patients some with high and others with medium or low levels of silicone antibodies, MBP antibodies did not correspond to the silicone antibody levels. Similarly human serum albumin antibodies which was significantly higher in patients with silicone implants did not correlate with levels of silicone antibodies. These results indicate that immune reaction to silicone and different tissue antigens do occur and they are initiated through different mechanisms. and since predominant antibody class against silicone, MBP and HSA was IgM, clonal activation of IgM is possible which certainly warrants further investigation.