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UNACCEPTABLE ANTIGEN IDENTIFICATION INCREASES THE PERCENTAGE OF COMPATIBLE FINAL CROSSMATCHES.
Kim Holden BS, CHS and Ellen Klohe PhD . Spokane WA, Inland NW Blood Center, 99201, HLA Laboratory .

One Lambda FlowPRA™ Single Antigen and Class II Specific beads are used to identify unacceptable antigens for all sensitized patients on our kidney waiting list. Potential donors are screened for unacceptable antigens for each patient on the waiting list by the UNOS match list run. This in addition to a preliminary crossmatch has resulted in the ability to predict final flow crossmatch results in the majority of cases and has significantly reduced the number of incompatible final crossmatches. Unacceptable antigens were identified using FlowPRA™ Single Antigen and Class II Specific antibody identification assays (One Lambda, Inc.). Samples were acquired on a FACScan™ flow cytometer (Becton-Dickinson). Forty-nine final crossmatches were analyzed on patients awaiting cadaveric kidney transplants for 2002 (post-bead era) while 71 final crossmatches were considered from 1999 and 2000 (pre-bead era). No changes were made to the flow crossmatch procedure during the study period. T cell AHG and B cell Amos techniques were used for preliminary crossmatches. Zero antigen mismatches were excluded from the analysis. Overall, 90% of patients had compatible final crossmatches in 2002 compared to 69% prior to bead use. 36% of transplants were in patients with ≥ 80% PRA compared to 0% and 13% in 1999 and 2000 respectively. Table 1 shows the % of compatible crossmatches stratified by PRA level.

PRAPre-Bead EraPost-Bead Era
0%93%100%
20-80%43%100%
>80%21%69%


In conclusion, an accurate evaluation of patients’ unacceptable antigens through use of FlowPRA™ Single Antigen and Class II Specific beads allow excellent predictions of final crossmatch results and may facilitate regional sharing for high PRA patients.