title: Increased erythrocyte C4D is associated with known alloantibody and autoantibody markers of antibody-mediated rejection in human lung transplant recipients.
abstract: BACKGROUND
  Immune responses to mismatched donor human leukocyte antigens (HLA) are important in the pathogenesis of chronic rejection. This study evaluated whether erythrocyte-bound C4d (E-C4d) is associated with known alloimmune and autoimmune markers of antibody-mediated rejection after human lung transplantation (LTx).
  
  
  METHODS
  Flow cytometry was used to analyze 22 LTx recipients and 15 healthy individuals for E-C4d. Development of antibodies to donor-mismatched HLA (donor-specific antibody [DSA]) and antibodies to HLA were determined using the solid-phase method by Luminex. Development of antibodies to self-antigens, K-alpha-1-tubulin (KA1T) and collagen V (Col-V), were measured by enzyme-linked immunosorbent assay. C3d deposition in lung biopsy specimens was determined by immunohistochemical staining.
  
  
  RESULTS
  Percent E-C4d (%E-C4d) levels were 19.9% in LTx patients vs 3.7% in healthy individuals (p = 0.02). DSA+ patients had higher E-C4d levels than DSA- patients (34.1% vs 16.7%, p = 0.02). In 5 patients with preformed anti-HLA, E-C4d levels were not significantly different vs 13 patients without detectable anti-HLA (p = 0.1). E-C4d levels were higher in patients who developed antibodies to KA1T (p = 0.02) and Col-V (p = 0.03). Recipients with C3d-positive tissue deposition had higher E-C4d levels than patients with C3d-negative biopsy results (p = 0.01).
  
  
  CONCLUSIONS
  Increased %E-C4d levels are found in patients with positive DSA, high antibody titers to KA1T and Col-V, and have C3d+ lung biopsy findings. Therefore, %E-C4d can serve as a potential marker for antibody-mediated rejection after LTx.
authors.affiliation: Department of Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Angali
authors.initials: A
authors.lastname: Golocheikine
authors.forename: Dilip S
authors.initials: DS
authors.lastname: Nath
authors.forename: Haseeb Ilias
authors.initials: HI
authors.lastname: Basha
authors.forename: Deepti
authors.initials: D
authors.lastname: Saini
authors.forename: Donna
authors.initials: D
authors.lastname: Phelan
authors.forename: Aviva
authors.initials: A
authors.lastname: Aloush
authors.forename: Elbert P
authors.initials: EP
authors.lastname: Trulock
authors.forename: Ramsey R
authors.initials: RR
authors.lastname: Hachem
authors.forename: G Alexander
authors.initials: GA
authors.lastname: Patterson
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Ahearn
authors.forename: Thalachallour
authors.initials: T
authors.lastname: Mohanakumar
mesh_terms: D000906:Antibodies / Q000097:blood*; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001706:Biopsy; D016022:Case-Control Studies; D024062:Collagen Type V / Q000276:immunology; D015933:Complement C3d / Q000378:metabolism; D015935:Complement C4b; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006084:Graft Rejection / Q000097:blood / Q000276:immunology*; D006801:Humans; D007518:Isoantibodies / Q000097:blood*; D008168:Lung / Q000378:metabolism / Q000473:pathology; D016040:Lung Transplantation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood*; D011446:Prospective Studies; D011951:Receptors, Complement / Q000097:blood; D014404:Tubulin / Q000276:immunology
chemical_list: D000906:Antibodies; D001323:Autoantibodies; D015415:Biomarkers; D024062:Collagen Type V; D007518:Isoantibodies; D010446:Peptide Fragments; D011951:Receptors, Complement; D014404:Tubulin; D015933:Complement C3d; D015935:Complement C4b; C032261:complement C4d