Lung-restricted antibodies mediate primary graft dysfunction and prevent allotolerance after murine lung transplantation

Abstract

Over one-third of lung recipients have preexisting antibodies against lung-restricted antigens: collagen (Col) type V and K-a1 tubulin (KAT). Although clinical studies have shown association of these antibodies with primary graft dysfunction (PGD), their biological significance remains unclear. We tested whether preexisting lungrestricted antibodies can mediate PGD and prevent allotolerance. A murine syngeneic (C57BL/6) or allogeneic (C57BL/6 toBALB/c) left lung transplantation model was used. Rabbit polyclonal antibodies were produced againstKATandCol-V and injected pretransplantation. T cell frequency was analyzed using enzyme-linked immunospot, whereas alloantibodies were determined using flow cytometry. Wet:dry ratio, arterial oxygenation, and histology were used to determine PGD. Preexisting Col-V or KAT, but not isotype control, antibodies lead to dose-dependent development of PGDafter syngeneic lung transplantation, as evidenced by poor oxygenation and increased wet:dry ratio.Histology confirmed alveolar and capillary edema. The native right lung remained unaffected. Epitope spreading was observed where KAT antibody treatment led to the development of IL-17-producing CD4+ T cells and humoral response against Col-V, or vice versa. In contrast, isotype control antibody failed to induceCol-V-or KAT-specific cellular orhumoral immunity. Inaddition,noneof themicedevelopedimmunity against a non-lung antigen, collagen type II. Preexisting lung-restricted antibodies, but not isotype control, prevented development of allotolerance using the MHC-related 1 and cytotoxic T-lymphocyteassociated protein 4-Ig regimen. Lung-restricted antibodies can induce both early and delayed lung graft dysfunction. These antibodies can also cause spreading of lung-restricted immunity and promote alloimmunity. Antibody-directed therapy to treat preexisting lung-restricted antibodies might reduce PGD after lung transplantation.