Increased erythrocyte C4D is associated with known alloantibody and autoantibody markers of antibody-mediated rejection in human lung transplant recipients
published online 18 December 2009.
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-α-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.
aDepartment of Surgery, Washington University School of Medicine, St. Louis, Missouri
bDepartment of Pathology & Immunology, Washington University School of Medicine, St. Louis, Missouri
cDepartment of Medicine, Washington University School of Medicine, St. Louis, Missouri
dCardiothoracic Surgery, Washington University School of Medicine, St. Louis, Missouri
eHLA Laboratory, Barnes-Jewish Hospital, St. Louis, Missouri
fDepartment of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
Reprint requests: T. Mohanakumar, PhD, Washington University School of Medicine, Department of Surgery, Box 8109-3328 CSRB, 660 S Euclid Ave, St. Louis, MO 63110. Telephone: 314-362-8463. Fax: 314-747-1560
ABSTRACT