title: HLA-DP antibodies before and after renal transplantation.
abstract: Human leukocyte antigen (HLA)-DP is considered a target for humoral immune response in clinical transplantation. This study analyses the incidence of HLA-DP antibodies in renal patients. Development and epitope specificity of donor-specific antibodies (DSA) and non-DSA (NDSA) were examined. Pre- and posttransplant sera of 338 patients were screened for HLA-DP antibodies using the luminex single antigen assay. Positive patients, partners and/or kidney donors were HLA-DP typed by sequence-specific oligonucleotides. Potential epitopes were mapped by comparing the amino acid sequences of HLA-DP hypervariable regions (HVR) A-F of recipient, partner and/or donor. Specificities in the sera were aligned to deduce the HVR motif responsible for the antibodies. HLA-DP antibodies were detected in 14% of the patients (48/338). Before transplantation, the antibodies were shown in 23% (10 females and 1 male) and 77% were found after transplantation (30 in patients after the first, 7 after the second graft). Specificities were never restricted to individual mismatched antigens; broad HLA-DP sensitization was found as a rule. A single HVR mismatch was present in 80% of the DSA and in 79% of the NDSA. No HLA-DPA specific antibodies were found. Our findings confirm that HLA-DP antibodies are specific for epitopes shared by different HLA-DP antigens, indicating that only a restricted number of mismatched epitopes are recognized by the recipients immune system. Matching for immunogenic HLA-DP epitopes for renal transplantation seems to be functionally more relevant than classical matching at the allelic level.
authors.affiliation: Transplantation Immunology, Tissue Typing Laboratory, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: E V A
authors.initials: EV
authors.lastname: Billen
authors.forename: M H L
authors.initials: MH
authors.lastname: Christiaans
authors.forename: I I N
authors.initials: II
authors.lastname: Doxiadis
authors.forename: C E M
authors.initials: CE
authors.lastname: Voorter
authors.forename: E M
authors.initials: EM
authors.lastname: van den Berg-Loonen
mesh_terms: D000906:Antibodies / Q000276:immunology*; D000917:Antibody Formation / Q000276:immunology; D016022:Case-Control Studies; D022801:Complementarity Determining Regions / Q000276:immunology; D000939:Epitopes / Q000032:analysis / Q000276:immunology; D005260:Female; D006682:HLA-DP Antigens / Q000276:immunology*; D059867:HLA-DP alpha-Chains; D006801:Humans; D016030:Kidney Transplantation / Q000276:immunology*; D008297:Male; D014019:Tissue Donors
chemical_list: D000906:Antibodies; D022801:Complementarity Determining Regions; D000939:Epitopes; D006682:HLA-DP Antigens; D059867:HLA-DP alpha-Chains; C071695:HLA-DPA antigen