LPS INCREASES BIOMATERIAL DEGRADATION BY HUMAN MONOCYTES IN-VITRO

Different cell lines are involved during an immunological reaction, pr incipally lymphocytes and monocytes. Monocyte/macrophage cells, which are among the first to appear in wound-healing and infection sites, ar e largely implicated in phagocytosis and could be involved in calcium- phosphate degradation. Their role in these processes may relate to cyt okine secretions and/or their sensitivity to certain cytokines. We tes ted the behavior of human monocytes placed on the surface of biphasic calcium-phosphate (BCP) tablets in the presence of two lipopolysacchar ide (LPS) concentrations. After short-term culture (48 h), cytokine re lease (IL-(1 beta), IL-6) was measured by ELISA, and morphological cel l events and biomaterial degradation were observed in scanning electro n microscopy. BCP surface pits were noted near cells stimulated by 0.5 mu g/mL LPS but were not apparent with 10 mu g/mL LPS. The number of lacunae on BCP was increased after LPS treatment of human monocytes. A n upmodulation of IL-(1 beta) and IL-(6) (in culture medium) released by LPS-activated human monocytes was observed, indicating good cell st imulation. This study demonstrates that LPS-activated human monocytes can degrade the surface of calcium-phosphate ceramic and confirms the role of human monocytes in biomaterial degradation. (C) 1997 John Wile y & Sons, Inc.