title: The dilemma of DQ HLA-antibodies.
abstract: Accurate identification of antibody reactivity against HLA-DQ antigens was difficult by using the old serological assays because of the strong linkage disequilibrium between HLA-DR and HLA-DQ (the usual inheritance of a certain HLA-DR molecule that ties together with the same DQ molecule within a racial group). The accurate and precise identifications of anti-HLA-antibodies of DQ specificities were made possible with the introduction of multiplex-bead arrays (Luminex), using single antigen bead (SAB) assay. The SAB assay is also considered today to be the most sensitive and specific method for alloimmunization assessment even for the low titer anti-HLA-antibodies. However, it is becoming clear that the detection of the HLA antibodies by SAB is not absolutely perfect due to the variation in densities, conformations and orientations of the antigen coated beads. Unlike HLA-DR, the HLA-DQ antigens are made of two polymorphic chains, both (alpha and beta chains) can contribute to the process of immunization individually or jointly. Routine SAB testing approach, which assigns the specificities based on beta chains and ignores the contribution of the DQα chains, can lead to erroneous DQ-antibody assignments. Therefore, it is important to recognize both the peculiarity of the HLA-DQ antigens as well as the nature of the assay format used in order to reach the correct antibody assignments. Erroneous donor specific antibodies (DSA) assignment may lead to denial of an otherwise immunologically compatible organ transplant, or exposing transplant recipients to unnecessary investigations or immunosuppression. The following two patients presented with HLA-antibodies against DQ antigens (anti-DQ-Abs) highlight these two scenarios.
authors: Histocompatibility & Immunogenetics Laboratory (HIL), King Fahad Specialist Hospital-Dammam, Dammam, Saudi Arabia.
authors: Rabab
authors: R
authors: Al Attas
authors: Histocompatibility & Immunogenetics Laboratory (HIL), King Fahad Specialist Hospital-Dammam, Dammam, Saudi Arabia.
authors: Dalal
authors: D
authors: Al Abduladheem
authors: Histocompatibility & Immunogenetics Laboratory (HIL), King Fahad Specialist Hospital-Dammam, Dammam, Saudi Arabia.
authors: Adel A
authors: AA
authors: Shawhatti
authors: Histocompatibility & Immunogenetics Laboratory (HIL), King Fahad Specialist Hospital-Dammam, Dammam, Saudi Arabia.
authors: Ricardo
authors: R
authors: Lopez
authors: Histocompatibility & Immunogenetics Laboratory (HIL), King Fahad Specialist Hospital-Dammam, Dammam, Saudi Arabia.
authors: Abdelhamid
authors: A
authors: Liacini
authors: Histocompatibility & Immunogenetics Laboratory (HIL), King Fahad Specialist Hospital-Dammam, Dammam, Saudi Arabia.
authors: Saber
authors: S
authors: AlZahrani
authors: Multi Organ Transplant Center, King Fahad Specialist Hospital-Dammam, Dammam, Saudi Arabia.
authors: Khalid
authors: K
authors: Akkari
authors: Pathology and Laboratory Medicine, King Fahad Specialist Hospital-Dammam, Dammam, Saudi Arabia.
authors: Nasreen
authors: N
authors: Hasan
authors: Multi Organ Transplant Center, King Fahad Specialist Hospital-Dammam, Dammam, Saudi Arabia.
authors: Abdulnaser
authors: A
authors: Alabadi
mesh_terms: D000328:Adult; D000906:Antibodies / Q000097:blood; D003951:Diagnostic Errors / Q000517:prevention & control; D005190:Family; D005260:Female; D059848:HLA-DQ alpha-Chains / Q000235:genetics / Q000276:immunology*; D059866:HLA-DQ beta-Chains / Q000235:genetics / Q000276:immunology*; D006650:Histocompatibility Testing / Q000379:methods*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D016030:Kidney Transplantation; D008297:Male; D008863:Microspheres; D012680:Sensitivity and Specificity; D014019:Tissue Donors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000906:Antibodies; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains