CYTOIMMUNOLOGICAL MONITORING AFTER HOMOGRAFT VALVE-REPLACEMENT

Examination results concerning immunological reactions in cryopreserve d allograft valves during the early postoperative course are so far no t available. Cytoimmunological monitoring (CIM) is a well established method to prove rejection reaction after allograft transplantation and was used in this study. Allograft valves were harvested from patients who underwent heart transplantation, and did not require sterilizing in antibiotic solutions. The valves were dissected, conserved and subs equently frozen to -40-degrees-C and stored in a freezing system at -1 96-degrees-C. During the first 3 weeks following allograft implantatio n, CIM was performed daily. An activation index (AI) was determined fr om the cytological evaluation of the mononuclear concentrate in the pe ripheral blood. An increase of the AI>1 was defined as an immunologica l reaction. As control we performed 98 CIM examinations in eight patie nts who underwent bioprosthetic valve replacement in the aortic positi on. Echocardiography (TTE and TEE) was used postoperatively as functio n control. Out of 16 patients who underwent cryopreserved aortic valve implantation in the aortic position, 336 CIM-results were obtained. A n immunological reaction could be detected in all patients, starting o n the 5th day on average. Comparing ABO-compatible (group I, n=9) with ABO-incompatible (group II, n=7) allografts, the AI-maximum in group I was 1.4 with a mean duration of 1.5 days. Group II was characterized by more intensive immunoreactions (xBAR=2.3) which proved to be even more prolonged (xBAR=3.3 days, P<0.05). Nevertheless it became apparen t that all observed immunological events were completely reversible wi thout the need for immunosuppressive drugs. Cytoimmunological monitori ng control in patients after bioprosthetic valve replacement did not s how any signs of activation (n=98, xBAR=0.1). Routine echocardiography demonstrated a regular function and morphology of the implanted allog rafts in 14 cases after 3 months. A hemodynamically irrelevant valve i nsufficiency could be detected in two patients. Allograft valves Gener ally cause immunological reactions in contrast to xenogeneic bioprosth eses as measured in the CIM routine test. The activation index of ABO- incompatible allografts shows significantly more and longer elevation. The immunological reactions reverse spontaneously without any use of immunosuppression. A different ABO-system does not alter the function and morpholoy of the allograft valves early postoperatively. However, the role of ABO tissue-matching should be clarified in the long-term f ollow-up.