The vascular endothelium as target of humoral auto-reactivity in myocarditis and rejection

The vascular endothelium plays a key role in immunologic reactions that also involve the heart: Increased expression of class 1 and 2 antigens of the major histocompatibility complex a common finding in acute rejection after heart transplantation whereas in myocarditis this finding is less pronounced. Another form of involvement of the endothelial cells in the secondary immune response has been reported only infrequently; anti-endothelial antibodies, which may be cytolytic to living cultured human endothelial cells, were demonstrated to be bound to the endomyocardial biopsies of patients with different forms of rejection and with biopsy proven myocarditis and circulating in the peripheral blood of the patients as cytolytic autoantibodies.