title: Serum flow cytometric C1q binding antibody analysis of renal recipients with low levels of sensitization.
abstract: OBJECTIVE
  Patients displaying flow cytometric crossmatch results within the grey zone of positivity are hard to evaluate, especially if they are undergoing their first transplantation. For these patients assays of donor-specific anti-HLA (human leukocyte antigen) antibodies with complement-fixing properties to cause cell lysis are important for antibody-mediated rejection and graft failure. The aim of this study was to detect the relevance of serum C1q-binding antibodies detected in renal recipients with grey zone crossmatch reactivity who were considered to show low levels of sensitization against their potential donors.
  
  
  METHODS
  This study includes 114 patients who were admitted for their first renal transplantation between September 2009 and August 2011, including 33 subjects considered by flow cytometric cross-match to be the sensitized group, whereas the remaining 81 recipients had negative results. We analyzed the accumulation of serum the immunoglobulin (Ig)G bound C1q on HLA-coated flow cytometric panel reactive antibody (FlowPRA) beads. The serum samples were retrospectively analyzed with [C1q]FlowPRA (HLA class I and II), which were collected during the pretransplantation period every 6 months and every week posttransplantation within the first month and every 3 months thereafter. All serum samples were analyzed for the presence of anti-FlowPRA IgG alloantibody. We compared the C1q FlowPRA-positive and-negative groups for the number of posttransplantation days that the serum creatinine level was below <2 mg/dL as a metric of graft function.
  
  
  RESULTS
  With a mean follow-up of 492 ± 84 days, there was a significant difference between flow cytometric crossmatch results and creatinine decrease rate (P = .02). The serum creatinine decrease rates of the 9 C1q-positive versus the 15 C1q-negative subjects showed significant difference (P < .05).
  
  
  CONCLUSIONS
  C1q-binding antibody analysis shows the presence of serum antibodies capable of complement binding and antibody-mediated rejection, which could be useful to assess rejection risk among the "grey zone" of renal recipients with low levels of sensitization against their donors.
authors: Genetic Diseases Diagnosis Center, Molecular Genetics Laboratory, Haydarpasa Numune Research and Training Hospital, Istanbul, Turkey. pinaren@gmail.com
authors: P
authors: P
authors: Ata
authors: M
authors: M
authors: Canbakan
authors: M
authors: M
authors: Kara
authors: L
authors: L
authors: Özel
authors: E
authors: E
authors: Ünal
authors: M İ
authors: Mİ
authors: Titiz
mesh_terms: D000328:Adult; D015922:Complement C1q / Q000276:immunology*; D003888:Desensitization, Immunologic; D046148:Donor Selection; D005260:Female; D005434:Flow Cytometry; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control; D006085:Graft Survival; D006680:HLA Antigens / Q000276:immunology; D006648:Histocompatibility; D006650:Histocompatibility Testing / Q000379:methods*; D006801:Humans; D007518:Isoantibodies / Q000097:blood*; D016030:Kidney Transplantation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014019:Tissue Donors; D016896:Treatment Outcome; D014421:Turkey
chemical_list: D006680:HLA Antigens; D007518:Isoantibodies; D015922:Complement C1q