Zeitschrift für klinische und zelluläre Immunologie
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Case Report: Anti-HLA-DQα Antibodies Have Clinical Impacts in Highly Immunized Kidney Patients

Lund KP, Hauge AW, Sørensen SS and Bruunsgaard H

Context and purpose: Organ exchange programmes are important in order to ensure organs to highly immunized kidney patients. In this case report, we describe a highly immunized patient in an acceptable mismatch program who had an unexpected positive Complement-Dependent Cytotoxicity (CDC) crossmatch with a deceased donor exchange.
Main findings: Subsequent evaluation revealed donor specific antibodies characterized by serological epitopes, which included the HLA-DQα chain, were masked in the standard IgG Luminex assay unless the serum was diluted; however, the antibodies demonstrated high MFI values when the serum was pretreated with EDTA or analyzed with the C1q assay. These findings led us to evaluate the extent of masked anti-HLA-DQ antibodies that included HLADQα/ DQβ pairs rather than just the HLA-DQβ chains in 16 highly immunized patients on the kidney transplantation waiting list at our transplantation center. We determined that 25% of the patients had antibodies directed towards serological epitopes that involved the anti-HLA-DQα chain but were masked in the standard IgG assay.
Principal conclusions: We conclude that masked anti-HLA-DQ antibodies directed towards serological epitopes that also involves the HLA-DQα chain are common and should be considered as they may cause a positive CDC crossmatch. Thus, donor specific HLA-DQ antibodies must be evaluated in relation to full HLA-DQα; DQβ pairs in the serological molecules of the donor.