Antiendothelial antibodies in sera of patients with infective endocarditis

Infective endocarditis is characterized by the colonization of endocardium by microorganisms. Except for Staphylococcus aureus, microorganisms are not able to adhere to and grow on endocardial cells; prior damage, e.g., by sh ear stress or other mechanical factors, is necessary. But other causes may well have a share. This study was, therefore, designed to identify immunolo gical factors, especially antibodies against endothelial cells, which could contribute to the initiation of endocardial injury. Sera of patients with infective endocarditis and healthy controls were inve stigated for the presence of antibodies against endothelial antigen. As the antigen source human umbilical vein endothelial cells were used. Antibodie s against endothelial cells were detected by indirect immunofluorescence, E LISA, immunoblotting, antibody dependent cellular cytotoxicity, and antibod y mediated cytotoxicity. Antibodies against endothelial cells were found in seven out of fifteen pat ients. These antibodies were directed against cytoplasmic structures and on ly appeared in the course of the disease. A correlation between the presenc e of these antibodies and disease activity or the outcome of disease was no t observed. These antibodies may develop as a consequence of damage to endo cardial cells (thereby exposing intracellular antigen to the immune system) and do not seem to play a role in the pathogenesis of infective endocardit is.