Abstract
BACKGROUND: The role of non-complement activating antibodies (ncAbs) to mismatched donor human leukocyte antigen (HLA) in the pathogenesis of chronic lung rejection is not known. We used a murine model of obliterative airway disease (OAD) induced by Abs to major histocompatibility major histocompatibility complex (MHC) class I and serum from donor-specific Abs developed in human lung transplant (LTx) recipients to test the role of ncAbs in the development of OAD and bronchiolitis obliterans syndrome (BOS).
METHODS: Anti-MHC ncAbs were administered intrabronchially in B.10 mice or in C3 knockout (C3KO) mice. Lungs were analyzed by histopathology. Lymphocytes secreting interleukin (IL)-17, interferon-gamma, or IL-10 to collagen V and K-alpha 1 tubulin (K alpha 1T) were enumerated by enzyme-linked immunospot assay. Serum antibodies to collagen V and K alpha 1T were determined by enzyme-linked immunosorbent assay. Cytokine and growth factor expression in lungs was determined by real-time polymerase chain reaction. Donor-specific Abs from patients with BOS and control BOS-negative LTx recipients were analyzed by C1q assay.
RESULTS: Administration of ncAbs in B.10 mice or C3KO resulted in OAD lesions. There were significant increases in IL-17- and interferon-gamma-secreting cells to collagen V and K alpha 1T, along with serum Abs to these antigens. There was also augmented expression of monocyte chemotactic protein-1, IL-6, IL-1 beta, vascular endothelial growth factor, transforming growth factor-beta, and fibroblastic growth factor in mice administered ncAbs by Day 3. Among 5 LTx recipients with BOS, only 1 had C1q binding donor-specific Abs.
CONCLUSION: Complement activation by Abs to MHC class I is not required for development of OAD and human BOS. Therefore, anti-MHC binding to epithelial and endothelial cells can directly activate pro-fibrotic and pro-inflammatory cascades leading to immune response to self-antigens and chronic rejection. J Heart Lung Transplant 2012; 31: 1214-1222 (C) 2012 International Society for Heart and Lung Transplantation. All rights reserved.