Repeated exposure to silicone gel can induce delayed hypersensitivity

Area of Science:

• Immunology
• Biomaterials Science

Background:

• The immunologic reactivity of silicone gel is debated.
• A quantitative lymphocyte localization assay in sheep is established for studying immune responses.

Purpose of the Study:

• To determine if silicone gel can induce an antigen-specific immune response, specifically delayed-type hypersensitivity.
• To assess lymphocyte-mediated responses to silicone gel after repeated exposure.

Main Methods:

• Sheep were sensitized with silicone gel, Freund's Complete Adjuvant (FCA) with silicone gel, FCA alone, or saline.
• Lymphocyte accumulation in skin lesions after intradermal challenge with silicone gel was measured using indium-111 labeled lymphocytes.
• Radioactivity counts in skin lesions indicated lymphocyte infiltration.

Main Results:

• Silicone gel-primed sheep showed significantly increased lymphocyte accumulation in silicone gel challenge sites compared to controls.
• The positive control (purified protein derivative) and negative control (saline) showed expected lymphocyte accumulation.
• Freund's Complete Adjuvant homogenized with silicone gel also induced significant lymphocyte accumulation.

Conclusions:

• The findings suggest that silicone gel may induce an antigen-specific, lymphocyte-mediated immune response.
• This indicates a potential for delayed-type hypersensitivity to silicone gel.
• Further research is warranted to elucidate the immunologic potential of silicone gel.