Unexpected anti-HLA-DR and -DQ alloantibodies after nephrectomy of an HLA-DR and -DQ identical first renal transplant.

The development of the single antigen beads assay by Luminex technology enables accurate identification of allele-specific antibodies. Herein, we report the identification of donor-specific HLA-DR and -DQ antibodies in a first kidney transplant recipient who received a DR and DQ identical kidney transplant. The recipient was a non-sensitized, non-transfused male patient suffering from an end-stage renal failure due to focal and segmental glomerulosclerosis. Two weeks after graft nephrectomy, anti-class I (donor-specific and non-donor specific) and class II antibodies were detected. The single antigen beads technique identified class II antibodies directed against DRB3*0202 and HLA-DQB1*0603 alleles. High-resolution class II typing revealed five allelic incompatibilities between donor and recipient. Amino-acid sequence alignment showed why this post-transplant highly immunized patient developed only these two allele-specific antibodies. Minimizing HLA mismatches between donor and recipient is important, but it is also useful to consider the combination of all HLA molecules present in the donor and recipient in order to define the antibody epitopes responsible for alloantibody responses.