THE RELEVANCE OF FLOW PRA I AND II SCREENING TESTS IN RENAL TRANSPLANT RECIPIENT

THE RELEVANCE OF FLOW PRA I AND II SCREENING TESTS IN RENAL TRANSPLANT RECIPIENT.
A Piazza, L Borrelli, PI Monaco, E Poggi, C Cortini, M Valeri, N Torlone, CU Casciani and D. Adorno. CNR Institute of Tissue Typing - Unit of Rome, Italy.

HLA antibodies screening in renal transplant recipient sera has historically been performed using complement dependent cytotoxicity (CDC) technique. Nevertheless the accuracy of this assay may be reduced by the presence of autologous antibodies or a low titer of alloantibodies. In the attempt to accurately identify and characterize HLA alloantibodies, 180 serum samples from 146 candidate transplant patients, previously screened using Amos-CDCPRA, were studied using FlowPRA class I and class II beads. The results were analyzed according to CDCPRA data and the kind of sensitization (transfusion, pregnancy or previous transplant). Concordance between CDCPRA and FlowPRA I was 77.8%. Twenty-one serum samples (11.7%) were FlowPRA class I+/CDCPRA- and nineteen (10.5%) FlowPRA I-/CDCPRA+. As far as the percentages of PRA positivity were concerned, the mean PRA level was significantly higher for FlowPRA I than for CDCPRA (64.5585 ± 26.7434% vs 38 ± 26%, p< 0.0001). Analyzing both class I and II FlowPRA results we found that CDCPRA were positive in 80% of FlowPRA I and II positive serum samples and in 63.1% of only FlowPRA I positive samples. Correlating kind of patient sensitization to FlowPRA I and II and CDCPRA results we highlighted that incidence of previous transplanted patients was significantly higher in FlowPRA I and II positive patients than in FlowPRA I positive (77.8% vs 41.9%, p = 0.00577). On the other hand the incidence of woman patients who had had a pregnancy was significantly higher in FlowPRA I positive than in FlowPRA I and II positive (61.3% vs 29.6%, p = 0.01537) patients. We found the FlowPRA beads screening test more sensitive and specific than the CDCPRA assay and believe it may prove helpful in revealing and characterizing the real sensitization of patients with history of immunizing events such as pregnancy or transplantation.