In vitro detection of C4d-fixing HLA alloantibodies: associations with capillary C4d deposition in kidney allografts

Am J Transplant. 2008 Jan;8(1):41-9. doi: 10.1111/j.1600-6143.2007.01998.x. Epub 2007 Nov 5.


Capillary C4d deposition is a valuable marker of antibody-mediated rejection (AMR). In this analysis, flow cytometric detection of alloantibody-triggered C4d deposition to HLA antigen-coated microparticles ([C4d]FlowPRA) was evaluated for its value as a marker for C4d deposition in renal allografts. For comparative analysis, 105 first renal biopsies performed for graft dysfunction and an equal number of concurrent sera were subjected to immunohistochemistry and [C4d] plus standard [IgG]FlowPRA, respectively. C4d deposition/fixation was detected in 17 biopsies and, applying [C4d]FlowPRA HLA class I and II screening, also in a small number of corresponding sera (N = 20). IgG reactivity detected by standard [IgG]FlowPRA was more frequent (49% of sera). Comparing [C4d]FlowPRA screening with capillary C4d staining, we found a high level of specificity (0.92 [95% confidence interval: 0.86-0.98]), which far exceeded that calculated for [IgG]FlowPRA (0.60 [0.50-0.70]). [IgG]FlowPRA screening, however, turned out to be superior in terms of sensitivity (0.94 [0.83-1.05] vs. 0.76 [0.56-0.97] calculated for C4d-fixing panel reactivity). Remarkably, posttransplant single antigen testing for identification of complement-fixing donor-specific alloreactivities failed to improve the predictive value of FlowPRA-based serology. In conclusion, our results suggest that detection of complement-fixing HLA panel reactivity could provide a specific tool for monitoring of C4d-positive AMR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Capillaries / immunology
  • Capillaries / metabolism
  • Complement C4b / metabolism*
  • Complement Fixation Tests
  • Female
  • HLA Antigens / immunology*
  • Humans
  • Isoantibodies / analysis*
  • Isoantibodies / physiology
  • Kidney / blood supply*
  • Kidney / immunology
  • Kidney / metabolism*
  • Kidney Transplantation / immunology*
  • Male
  • Middle Aged
  • Peptide Fragments / metabolism*
  • Transplantation, Homologous


  • HLA Antigens
  • Isoantibodies
  • Peptide Fragments
  • Complement C4b
  • complement C4d