6.916667
#10-OR
ALLELE-SPECIFIC HLA ALLOANTIBODIES AND IMPLICAITONS FOR ORGAN ALLOCATION.
Robert A. Bray Ph.D. ¹ and Howard M. Gebel Ph.D. ¹. ¹ Pathology, Emory University, Atlanta, GA, USA .

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Recent advances in HLA antibody screening (ie; Microparticles coated with individual HLA molecules) have provided new tools for identifying alloantibodies in transplant patients including the ability to detect allele-specific alloantibodies. In this study, we report on 6 individuals whose HLA alloantibody was restricted to a unique HLA allele or group of alleles (Table). For 3 patients, an allele-specific antibody was observed following failure of a DR antigen matched renal allograft. Two patients made antibodies following blood transfusions and one patients antibody resulted from pregnancy.

Table 1

Pt. ID	Pt. HLA Type	Donor HLA Type	Alloantibody Detected
1	DRB1*0101	DRB1*0103	DRB1*0103
2	DRB1*0405	DRB1*0401	DRB1*0401, *0404, *0408
3	DRB1*0801	DRB1*0803	DRB1*0803
4	DRB1*0802	Unknown	DRB1*0801, *0803, *1303, *1313
5	A*6802	A*6801	A*6801
6	B*0801, B*4001	Unknown	B*2702

Assessment of the protein sequences showed that these antibodies recognized unique epitopes at predominantly antibody accessible sites. While the importance of allelic differences is well known in stem cell transplantation, their significance in solid organ transplantation has not been studied. High-resolution typing is not currently performed for solid organ transplantation but for selected highly-sensitized patients, the failure to discriminate allele-specific from antigen-specific antibodies can limit access to acceptable organs. We believe that our observations have important implications in renal allograft allocation. Specifically, among highly sensitized patients, the identification of allele-specific antibodies will be necessary to correctly predict a negative crossmatch.