Donor heart endothelial cells as targets for graft infiltrating lymphocytes after clinical cardiac transplantation.

The in vitro cytotoxic reactivity of allograft infiltrating cells cultured from endomyocardial biopsies was tested against endothelial cells (EC) isolated from the own donor heart. EC derived from pieces of atrium were found to be proper targets for graft infiltrating cytotoxic T cells from four patients. The specificity of this cytotoxicity was further analysed by cold target inhibition studies and blocking with anti-CD3, anti-CD4 or anti-CD8 monoclonal antibodies. The experiments revealed that, besides a clearly HLA directed recognition, a more heterogeneous, multispecific response can be found, which might be partially explained by the activity of EC specific T cell clones. We conclude that this system provides a valuable approach to investigate the reactivity of graft infiltrating cells against EC in relation to the clinical course of the transplantation.