In vitro reaction to orthopaedic biomaterials by macrophages and lymphocytes isolated from patients undergoing revision surgery

Periprosthetic tissues observed at sites of loose total joint implants exhi bit abundant macrophages, lymphocytes, fibroblasts and particulate debris. Macrophages phagocytose orthopaedic debris and release proinflammatory cyto kines, chemokines, matrix metalloproteinases and other substances. In addit ion, other cell types present in tissues harvested from the bone-implant in terface are thought to influence periprosthetic bone resorption. The presen t study examined the effects of polymethylmethacrylate (PMMA), cobalt chrom e molybdenum alloy (CoCr), and titanium-alloy particle challenge on macroph ages co-cultured with lymphocytes in vitro. Potential synergistic effects o f lymphocytes on macrophage activation were determined by measuring interle ukin-6 and tumor necrosis factor-a release following exposure to orthopaedi c biomaterial particles. Exposure of macrophages or macrophages co-cultured with lymphocytes to all three types of particles resulted in increased rel ease of interleukin-6 and tumor necrosis factor-a! at 48 h, when compared t o macrophages or macrophages co-cultured with lymphocytes, respectively, cu ltured in the absence of particles. Lymphocytes isolated from periprostheti c tissues secreted increased basal levels of cytokines relative to peripher al blood lymphocytes. Higher doses of PMMA and titanium-alloy particles sti mulated increased levels of cytokine release in the macrophage and macropha ge/lymphocyte groups. In contrast, a higher dose of CoCr particles (0.075% v/v) was not as effective as the 0.015% v/v dose, indicating probable CoCr toxicity. The macrophage/lymphocyte co-culture did not show synergism betwe en the two types of cells with respect to cytokine release. T-cells at the bone-implant interface may alter the biological response to particulate deb ris. (C) 2000 Elsevier Science Ltd. All rights reserved.