Cytotoxicity and macrophage cytokine release induced by ceramic and polyethylene particles in vitro

Although the response of macrophages to debris has been widely studied, it has never been compared with the cellular response to ceramic debris. Our a im was to investigate the cytotoxicity of ceramic particles (AI(2)O(3) and ZrO2) and to analyse their ability to stimulate the release of inflammatory mediators compared with that of high-density polyethylene particles (HDP). We analysed the effects of particle size, concentration and composition us ing an in vitro model. The J774 mouse macrophage cell line was exposed to c ommercial particles in the phagocytosable range (up to 4.5 mu m). AI(2)O(3) was compared with ZrO2 at 0.6 mu m and with HDP at 4.5 mu m. Cytotoxicity tests were performed using how cytometry and macrophage cytokine release wa s measured by ELISA. Cell mortality increased with the size and concentration of Al2O3 particles , When comparing AI(2)O(3) and ZrO2 at 0.6 mu m, we did not detect any sign ificant difference at the concentrations analysed (up to 2500 particles per macrophage), and mortality remained very low (less than 10%), Release of T NF-alpha also increased with the size and concentration of AI(2)O(3) partic les, reaching 195% of control (165 pg/ml v 84 pg/ml) at 2.4 mu m and 350 pa rticles per cell (p < 0.05). Release of TNF-alpha was higher with HDP than with AI(2)O(3) particles at 4.5 mu m. However, we did not detect any signif icant difference in the release of TNF-alpha between AI(2)O(3) and ZrO2 at 0.6 mu m (p > 0.05).