Relevance of posttransplant flow cytometric T- and B-cell crossmatches in tacrolimus-treated renal transplant patients.

BACKGROUND: De novo development of anti-human leukocyte antigen (HLA) antibodies after transplantation is associated with increased rejection and decreased graft survival. In this study, the effect of posttransplant HLA antibodies on clinical outcome was evaluated in patients treated with tacrolimus by means of flow cytometric crossmatches (FCXm). METHODS: T- and B-cell FCXm were performed retrospectively on posttransplant sera of patients who received a graft between 1997 and 1999. Ninety-four kidney-only recipients were tested and all FCXm positive sera were investigated for the presence of HLA class I and II antibodies by Flow panel reactive antibodies. RESULTS: From 94 patients with a negative pretransplant complement-dependent cytotoxicity crossmatch, seven (7%) showed a positive pretransplant FCXm. After transplantation the FCXm became positive in five patients (6%). The predictive value of a positive FCXm after transplantation, and the log-transformed relative change in fluorescence ratio between pretransplant and posttransplant serum, were not significant to rejection within six months, nor to graft survival censored for death. CONCLUSIONS: The presence of HLA antibodies before rejection or graft failure could only be shown in a minority of patients; most antibodies were detected after graft failure, especially after transplantectomy. Monitoring through antibody testing after transplantation on the basis of our results has no added value with tacrolimus-based immunosuppression.

Automated quantitative evaluation of diseased and nondiseased renal transplants with MR renography.

PURPOSE: To present a method of automated parametric quantification of dynamic MR enhancement curves of renal transplants and evaluate the disease-discriminating properties of the resulting MR renography (MRR) data. MATERIALS AND METHODS: This study included 27 patients with nondiseased renal transplants and eight patients with diseased renal transplants. The examination was repeated in 10 patients and the reproducibility of the enhancement parameters was estimated by analysis of variance (ANOVA). The disease-discriminating properties of the transplant volumes and enhancement parameters were tested with t-tests and logistic regression analysis. RESULTS: The enhancement parameters were reproducible. The mean medullary nephronal washout rate (lambda1) and cortical arterial blood volume (mu0) were lower in diseased renal transplants. The combination of these parameters was a strong predictor of renal transplant disease (area under ROC curve 0.98; 95% confidence interval 0.96-1.0). CONCLUSION: Automated parametric quantification of cortical and medullary enhancement is feasible and allows the accurate detection of nonsurgical disease in renal transplants by MRR.