T Cell-Mediated Immune Response to Silica in Silicone Breast Implant Patients

Abstract

During the last 25 or more years, silicone has been used as a filler in breast implants and is the major constituent of the outer elastomer. It was once thought to be biologically and metabolically inert; however, studies strongly suggested that silicone can be metabolized to lower molecular weight structures and that it deteriorates to silica [1–3]. Biologically, silicone has been shown to produce reactions by macrophages in vivo to promote the release of interleukin 1 [4], and to be antigenic with the production of antibodies to silicone [5] and to the native proteins that adhere to the silicone [6]. Recently, it has been shown that breast implant patients can develop T cell response to silicon dioxide [7,8], and to silicone [9]. In the studies with silicon dioxide, the primary form of silica used was a crystalline form, yet the form used in the outer elastomer was an amorphous silica. The present study undertook to further define the cell-mediated immune response to silica by evaluating the potential of blocking the reactions with an antibody directed against interleukin 2 (IL2). In addition, various forms of silica were tested in parallel with the crystalline form to determine if the silica form varied the immune recognition, and two elements not involved with silicone breast implants were tested to evaluate the specificity of T cell reactions in implant recipients.