Background. Inflammatory cytokines play an important role in the development of experimental obliterative airway disease (OAD) after transplantation. To further determine the immunologic mechanisms associated with OAD development, we used a murine tracheal transplant model in which a single mismatched HLA-A2 transgenic molecule is indirectly recognized by the recipient CD4+ T cells and then determined whether neutralization of several inflammatory cytokines affected the development of OAD. Methods. Tracheas from HLA-A2+ C57BL/6 mice were heterotopically transplanted into C57BL/6 mice. Recipients were treated with neutralizing antibodies against tumor necrosis factor (TNF), interferon-γ (IFN-γ), or interleukin-1 (IL-1). Allograft histology as well as anti HLA-A2 antibody development and T cell proliferative responses were determined at days +5, +15, +28, and +60. Results. Allografts in untreated and anti-IFN-γ-treated recipients demonstrated full development of OAD by day +28. Allografts in anti-TNF-treated recipients showed no evidence of OAD, even at day +60. Allografts in anti-IL-1-treated recipients showed airway epithelium changes by day +28 but minimal evidence of OAD by day +60. Spleen cells from untreated and anti-IFN-γ treated recipients showed significantly higher proliferative responses to HLA-A2+ cells, compared with syngeneic recipients (negative controls). In contrast, anti-TNF and anti-IL-1-treated recipients showed significantly lower proliferative responses to HLA-A2+ cells, compared with untreated recipients. Development of anti HLA-A2 antibodies was detected in all recipients by day +15, with the exception of those treated with anti-TNF. Conclusion. Among the inflammatory cytokines, TNF seems to play a crucial role in the immunopathology of OAD developed after transplantation.
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