An Obligatory Role for Lung Infiltrating B Cells in the Immunopathogenesis of Obliterative Airway Disease Induced by Antibodies to MHC Class I Molecules

Using a murine model, we demonstrated that endobronchial administration of antibodies (Abs) to major histocompatibility complex (MHC) class I results in cellular infiltration, epithelial metaplasia, fibrosis and obstruction of the small airways (obliterative airway disease [OAD]) mediated predominantly by Th17 responses to self-antigens. This resembles bronchiolitis obliterans syndrome developed following human lung transplantation. Since B cells play a crucial role in induction of autoimmune responses, we defined the role of B cells and its antigen presenting properties in induction of OAD in this study. Anti-MHC class I was administered endobronchially in B-/- and wild-type mice. In contrast to wild type, B-/- animals did not demonstrate cellular infiltration, epithelial metaplasia and obstruction of airways following anti-MHC. Frequency of K-a1 tubulin and CollagenV-specific IL-17 cells was significantly decreased in B-/- mice. As expected, Abs against self-antigens and germinal center formation were not developed in B-/- mice. Thus, we conclude that B cells and its antigen presenting capacity play an important role in induction of immune responses to self-antigens and immunopathogenesis of OAD following the administration of anti-MHC. Therefore, strategies to block B-cell and its antigen presenting functions should be considered for preventing the development of chronic rejection.