IL-8 and tumor necrosis factor alpha in heart valves from patients with infective endocarditis

The embedding of bacteria in the vegetation of infective endocarditis impedes the penetration of phagocytic cells. IL-8 has a stimulating effect on the immune system, particularly with respect to chemotaxis and activation of granulocytes. Tumor necrosis factor alpha (TNF-alpha) is 1 of the major proinflammatory cytokines. IL-8 and TNF-alpha were visualized by means of immunohistochemistry in paraffin-embedded heart valve biopsies from 6 patients with infective endocarditis who required cardiac surgery during the active phase of the infection. In 5/6 patients there were signs of inflammation, and in these patients IL-8- and TNF-alpha-containing cells were visualized in the heart valve stromas or vegetations. The largest numbers of IL-8-containing cells, and the greatest amount of inflammation, were seen in patients with short preoperative treatment courses. No such relationships were seen with respect to TNF-alpha-containing cells. These observations may suggest that the occurrence of IL-8-containing cells in infected heart valves could be used as a marker of disease activity.