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 exhibit abundant macrophages, lymphocytes, fibroblasts and particulate debris. Macrophages phagocytose orthopaedic debris and release proinflammatory cytokines, chemokines, matrix metalloproteinases and other substances. In addition, other cell types present in tissues harvested from the bone-implant interface are thought to influence periprosthetic bone resorption. The present study examined the effects of polymethylmethacrylate (PMMA), cobalt chrome molybdenum alloy (CoCr), and titanium-alloy particle challenge on macrophages co-cultured with lymphocytes in vitro. Potential synergistic effects of lymphocytes on macrophage activation were determined by measuring interleukin-6 and tumor necrosis factor-alpha release following exposure to orthopaedic biomaterial particles. Exposure of macrophages or macrophages co-cultured with lymphocytes to all three types of particles resulted in increased release of interleukin-6 and tumor necrosis factor-alpha at 48 h, when compared to macrophages or macrophages co-cultured with lymphocytes, respectively, cultured in the absence of particles. Lymphocytes isolated from periprosthetic tissues secreted increased basal levels of cytokines relative to peripheral blood lymphocytes. Higher doses of PMMA and titanium-alloy particles stimulated increased levels of cytokine release in the macrophage and macrophage/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 between the two types of cells with respect to cytokine release. T-cells at the bone-implant interface may alter the biological response to particulate debris.