Interleukin 15 production by macrophages in the implant interface membrane of aseptically loosened joint replacements.

The T lymphocytes are cells involved in immunologically mediated hypersensitivity reactions. They are found in the cellular infiltrate present in the interface membrane of aseptically loosened joint prostheses. Activation of these cells has been demonstrated but not the important cytokine, interleukin 2 (IL2) required for such activation. This study describes the localization of IL15 and its mRNA in macrophages in interface membranes associated with activated T lymphocytes which are proliferating (as is evident from HLA-DR and Ki67 expression, respectively). The findings provide further evidence for immune mediated processes in aseptic loosening of orthopaedic implants because IL15 has similar activities to IL2 in T lymphocyte activation. Copyright 1998 Kluwer Academic Publishers