Silicone Gel Enhances the Development of Autoimmune Disease in New Zealand Black Mice but Fails To Induce It in BALB/cAnPt Mice

Anecdotal evidence links silicone gel breast implants with the development of autoimmune connective tissue disease in women. To investigate whether silicone gel is capable of directly inducing and/or enhancing the development of autoimmune disease, female BALB/cAnPt (BALB/c) and New Zealand Black (NZB) mice were injected subcutaneously with silicone gel, pristane, a nonmetabolizable substance that can cause plasmacytomas in BALB/c and NZB mice, or saline and monitored for the development of glomerulonephritis and autoantibody production. NZB, but not BALB/c, mice spontaneously develop autoantibodies and an autoimmune hemolytic anemia by 12 months of age. Over a period of 10 months, biweekly screening for proteinuria revealed increases in urinary protein in NZB mice that received multiple injections of either silicone gel or pristane. In contrast, urinary protein was unaffected in identically treated BALB/c mice. Although, silicone gel had no effect on serum titers of anti-erythrocyte antibodies in NZB mice, the hematocrits were significantly decreased. Moreover, silicone gel both increased the concentration of IgM anti-type I collagen antibodies and skewed the immunofluorescent staining pattern of serum autoantibodies on HEp-2 cells. In contrast, silicone gel failed to induce the production of anti-erythrocyte or antinuclear antibodies in BALB/c mice and induced only slight increases in IgG anti-type I collagen antibodies. These results suggest that silicone gel can exacerbate the development of autoimmune disease in autoimmune NZB mice, but fails to induce disease in normal BALB/c mice. This is consistent with several epidemiological studies failing to demonstrate an increase in the incidence of autoimmune disease in women with breast implants. However, because silicone gel was able to exacerbate autoimmune disease in NZB mice, it may play a similar role in the development of autoimmune disease in a small percentage of women who are genetically susceptible to such diseases.