ADVERSE REACTIONS ASSOCIATED WITH MEDICAL DEVICE IMPLANTS

Medical prostheses that replace or enhance functions of different tiss ues and organs are often implanted into the human body. Although medic al device materials are selected for their physico-chemical properties and biocompatibility, the long term presence of foreign materials in the body may lead to adverse reactions. The two most commonly observed problems are chronic infections at the site of implant, and the forma tion of wear particles from implanted material. The particles spread t hroughout the organism and accumulate in various tissues inducing chro nic inflammation. The chronic inflammatory process, induced either by particles or by antigenic material, results in tissue damage and granu loma formation. Other problems, that have not been extensively studied , and may be associated with the long-term presence of foreign materia ls, are general effects on the host's immunocompetence. The relationsh ip between implants and development of autoimmune disorders and neopla sia has been reported. However, with relatively long latency for the d evelopment of such diseases, direct relationship is difficult to docum ent. The main research goal of our laboratory is to study effects of f oreign materials, either solid or in particulate form, on the host's i mmune functions. Macrophages, which are the cells mostly involved in t he inflammation process are being studied. Attention is focused on eva luation of the major macrophage functions, such as phagocytosis, antit umor activity, antigen presentation, and the regulatory cytokine produ ction. As macrophages play a pivotal role in generating immune respons es, any change in their functions may have significant effect on the e fferent end of the host's immunocompetence.