Increased erythrocyte C4D is associated with known alloantibody and autoantibody markers of antibody-mediated rejection in human lung transplant recipients.
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.
Golocheikine
Angali
A
Department of Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Nath
Dilip S
DS
Basha
Haseeb Ilias
HI
Saini
Deepti
D
Phelan
Donna
D
Aloush
Aviva
A
Trulock
Elbert P
EP
Hachem
Ramsey R
RR
Patterson
G Alexander
GA
Ahearn
Joseph M
JM
Mohanakumar
Thalachallour
T
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
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