Human leukocyte antigen mismatch and other factors affecting cryopreserved allograft valve function.

The causes of cryopreserved allograft heart valve degeneration are poorly understood. We investigated HLA mismatch and other factors implicated in allograft valve degeneration. For this study we recruited 110 adult recipients of allograft heart valves who underwent surgery between June 1998 and March 2003 in the state of Victoria, Australia. Recipients and donors were HLA typed using serological and molecular methods. Valve function at most recent echocardiographic follow-up was examined for an association with the following variables using univariate and multivariate methods: HLA-A,-B, and -DR donor-recipient mismatch; HLA class I mismatch; total HLA mismatch; valve ischemic time; recipient age; donor age; ABO blood group donor-recipient match; and allograft size. Mean recipient age was 45 years (18-75 years), 75% were men. Seventy-four pulmonary (62 Ross procedure) and 36 aortic allografts were examined. Median valve ischemic time was 31 hours, range 20-48 hours. Echocardiographic follow-up was complete at a mean of 41 (+/-18) months, range 6-85 months. At univariate analysis longer ischemic time and younger recipient age were associated with valve dysfunction. HLA-A, -B, or DR mismatch, HLA class I mismatch, total HLA mismatch, donor age, ABO mismatch, and allograft size were not associated with valve dysfunction. Only younger recipient age remained significant at multivariate analysis. In conclusion, longer ischemic times and younger patient age predicted valve dysfunction at a mean of 3 years follow-up. Recipient age remained the strongest predictor of valve dysfunction. These results indicate that allograft ischemic times should be minimized.

Anti-HLA antibodies after cryopreserved allograft valve implantation does not predict valve dysfunction at three-year follow up.

BACKGROUND AND AIM OF THE STUDY: As the cause of allograft heart valve degeneration is poorly understood, the study aim was to investigate the host antibody response to allograft valve implantation. METHODS: Sera were obtained from 92 recipients of allograft heart valves (61 pulmonary, 31 aortic). Sera were tested for anti-HLA class I antibodies by ELISA and complement-dependent cytotoxicity (CDC) methods, and anti-HLA class II antibodies by ELISA. Specificities of recipient anti-HLA class I antibodies were defined by standard CDC testing against a panel of T lymphocytes from 80 blood donors. Donor valve HLA typing was performed on stored donor DNA samples using molecular methods. The presence of donor-specific anti-HLA class I antibodies was hence defined in recipient sera. The presence of anti-HLA antibodies and donor-specific anti-HLA class I antibodies were correlated with function of allograft valves at the most recent echocardiographic follow up. RESULTS: At a mean of 3.0 years (range: 0.3-5.4 years) after allograft implantation, 96% (87/92) and 82% (75/92) of patients were positive for anti-HLA class I and II antibodies, respectively, by ELISA testing. Some 68% (61/90) of patients were positive for anti-HLA class I antibody (PRA > 5%) by CDC testing. PRA levels decreased with greater postoperative interval (r = -0.31, p = 0.003). In 68 recipients where donor HLA type was defined, 54% (37/68) of patients had antibodies specific to at least one donor HLA class I antigen. In 87 patients with a recent echocardiographic examination available for analysis (at a mean of 3.5 +/- 1.6 years postoperatively), there was no association between valve dysfunction and antibody status. CONCLUSION: Anti-HLA class I and II antibodies were detected by ELISA methods in most patients after allograft implantation extending to 5.4 years. The clinical significance of these findings is unclear, as no correlation was found between the prevalence of anti-HLA antibody and echocardiographic parameters of valve dysfunction at a mean of 3.5 years follow up.

Bacterial contamination of tissue allografts - experiences of the donor tissue bank of Victoria.

The aim of this study is to report the experience of the Donor Tissue Bank of Victoria with bacteria isolated from musculoskeletal, skin and cardiac allografts retrieved from cadaveric donors. The results of all quality control samples for bacterial culture, taken during retrieval and processing of allografts at the DTBV for a 12 month period, were extracted and analysed. It was found that 15.7% of skin, 15.1% of heart valves and 5.8% of musculoskeletal samples had positive culture results. The number and types of organisms isolated varied with tissue type. The most commonly isolated organisms were Staphylococcus species (including S. aureus). The identity of the isolate and the number of positive specimens from the same donor were considerations in the decision concerning the suitability of tissue for subsequent implantation.