1.2000
#22
USE OF MOLECULAR HLA TYPING AND SINGLE ANTIGEN BEAD FLOW CYTOMETRY ASSAYS IN THE EVALUATION OF CROSSMATCH RESULTS.
Jane Kearns, BS,CHS, Curtis Lind, BS,CHS, Erin Pierce, BS and Malek Kamoun, MD,PhD. Philadelphia PA, USA, University of Pennsylvania, 19104, Department of Pathology and Laboratory Medicine.

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Allocation of zero antigen mismatched kidneys is based on the matching at A,B,DR loci only. UNOS matching algorithm utilizes split level designations as defined by a national consensus. Consequently, difficult to define serological splits will match the broad antigen designations. This case illustrates the importance of matching at the serological split level, consideration of other HLA loci and the use of single antigen bead technology for evaluation of crossmatch results.
In March 2004, our center was offered a zero antigen mismatched kidney for a patient listed for transplant #3. The patient HLA type was A1,29, B57,70, DR4,13, DQ3. The donor HLA type was A1, B57,71, DR4,13. The patient was highly sensitized to mismatched antigens from the previous transplants. Antibody specificities included DQ1 which was listed in UNET as an unacceptable antigen. Donor DQ typing was not performed and therefore, not considered in the renal match. The probability of a positive B cell crossmatch was high due to the frequency of the DR13-DQ1 association. As expected, the B cell crossmatch was strongly positive, however, a positive T cell crossmatch was also observed. Molecular HLA typing was performed to confirm level of matching. Donor mismatched antigens were defined as B71(patient typed as B72) and Cw3. High resolution screening techniques were employed to identify donor specific antibodies. Single antigen beads (One Lambda) were tested and indicated the presence B71 antibody and absence of Cw antibodies.
Single antigen beads are a useful tool in the evaluation of crossmatch results and determination of unacceptable antigens, thereby, reducing the potential for positive final crossmatches.