Other monitored parameters will be: 1) the post transplant course and clinical status; the occurrence of graft dysfunction (echocardiographic monitoring will follow each endomyocardial biopsy), 2) the occurrence of cellular and/or humoral rejection in endomyocardial biopsies (8 protocolar endomyocardial biopsies within 12 months after heart transplantation), 3) presence and tissue distribution (vascular/non-vascular) staining for complement fragments C3 and C4 (markers of antibodies-mediated complement activation), 4) the period of cardiac allograft cold ischemia 5) aetiology of brain death of the donor 6) degree of HLA mismatch between donor and recipient, 7) blood cytokine levels involved in regulation of humoral immune response.