title: Assignment of C1q-binding HLA antibodies as unacceptable HLA antigens avoids positive CDC-crossmatches prior to transplantation of deceased donor organs.
abstract: Soon, a virtual crossmatch shall replace the complement-dependent cytotoxicity (CDC) allocation crossmatch in the Eurotransplant region. To prevent positive CDC-crossmatches in the recipient centre, careful definition of unacceptable antigens is necessary. For highly sensitized patients, this is difficult by CDC alone. Assignment of all antibodies detected by sensitive assays, however, could prevent organ allocation. To assess the usefulness of the Luminex C1q-assay to prevent positive CDC-crossmatches, all CDC-crossmatches performed prior to deceased kidney transplantation in a 16-month-period were reviewed. Sera causing positive crossmatches were investigated by the C1q-assay. 31 out of 1432 crossmatches (2.2%) were positive. Sera involved in 26 positive crossmatches were available. C1q-binding donor-specific antibodies were detected in 19 sera (73.1%). The other sera were from recipients without any HLA antibodies detectable by CDC or common solid phase assays. Three patients had known Non-HLA antibodies causing positive CDC-results. Four crossmatches were only weak positive. Therefore, avoidance of donors with HLA antigens against whom C1q-binding antibodies were detected would have prevented all positive crossmatches due to HLA antibodies. Provided that all HLA specificities against which antibodies are detected by the Luminex C1q-assay are considered as unacceptable antigens, CDC-crossmatches prior to transplantation might safely be omitted in many patients. They should be maintained in highly immunized patients, however, for whom assignment of all C1q-positive antibodies as unacceptable antigens could lead to a significant delay or even prevention of transplantation.
authors.affiliation: Institute of Transfusion Medicine, University Hospital of Schleswig-Holstein, Lübeck/Kiel, Germany. Electronic address: david.juhl@uksh.de.
authors.forename: David
authors.initials: D
authors.lastname: Juhl
authors.affiliation: Department of Transfusion Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Marget
authors.affiliation: Institute for Transfusion Medicine of Hannover Medical School, Hannover, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hallensleben
authors.affiliation: Institute of Transfusion Medicine, University Hospital of Schleswig-Holstein, Lübeck/Kiel, Germany.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Görg
authors.affiliation: Institute of Transfusion Medicine, University Hospital of Schleswig-Holstein, Lübeck/Kiel, Germany.
authors.forename: Malte
authors.initials: M
authors.lastname: Ziemann
mesh_terms: D015922:Complement C1q / Q000276:immunology*; D005260:Female; D006680:HLA Antigens / Q000276:immunology*; D006650:Histocompatibility Testing; D006801:Humans; D007518:Isoantibodies / Q000276:immunology*; D008297:Male; D016377:Organ Transplantation; D014019:Tissue Donors
chemical_list: D006680:HLA Antigens; D007518:Isoantibodies; D015922:Complement C1q
keywords: CDC-crossmatch; Complement-binding bead arrays; Luminex C1q-assay; Organ allocation; Virtual crossmatch