Body: A patient was screened for Donor Specific HLA Antibodies (DSA) as part of the workup for cardiac transplant. Testing resulted in detection of DQA1*05:01/DQB1*02:01 DSA at greater than 15,000 MFI, however, other DQB1*02 beads were negative based on transplant center criteria ( <5000 MFI). C1q testing was also positive for the DQA1*05:01/DQB1*02:01 combination at greater than 15,000 MFI. Initial DSA testing was performed using One Lambda (OLI) Thermo Fisher, LABScreen™ Single Antigen Class I & II reagents. Listing DQA1*05:01 as an unacceptable antigen in UNOS resulted in a CPRA of 41%. Discussions with the transplant center regarding this antibody and its potential to limit the donor pool caused our laboratory to further investigate and validate the presence of the DQA1*05:01 DSA. 2 surrogate flow cytometry crossmatches were performed with donors that had HLA typing of DQA1*05:01/DQB1*02:01. Both crossmatches were B-cell negative (and T-cell negative). Because the One Lambda LABScreen™ Single Antigen Class II panel contains only one bead that expresses the DQA1*05:01 allele, a review of the Werfen LIFECODES® Single Antigen Class II panel was performed. This panel contained 4 DQA1*05:01 beads with different DQB1 alleles: DQB1*04:01, *03:01, *02:02, & *02:01. Screening of the patient sample with LIFECODES® reagents resulted as negative for all DQA1*05:01/DQB1 combinations.
Conclusion: Using all the data from HLA Class II single antigen testing and surrogate crossmatches, the decision was made to not list the DQA1*05:01 as an UNOS unacceptable antigen. In addition, if standard testing indicates only the presence of DQA1*05:01 DSA, our laboratory now reflexes to testing on the Werfen LIFECODES® Class II Single Antigen panel. This case highlights the utility of multiple HLA antibody identification modalities to confirm results, including surrogate crossmatches. Fortunately, the patient was successfully transplanted (with donor that did not have DQA1*05:01/DQB1*02:01) and subsequent DSA monitoring has been negative.
