Ankit Bharat, Stephen Chiu, Zhikun Zheng, Haiying Sun, Anjana Yeldandi, Malcolm M. DeCamp, Harris Perlman, G. R. Scott Budinger, Thalachallour Mohanakumar

Over third of lung recipients have pre-existing antibodies against lung-restricted antigens, collagen type V (Col-V), and K-alpha1 tubulin (KAT). While clinical studies have shown association of these antibodies with primary graft dysfunction (PGD), their biological significance remains unclear. We tested whether pre-existing lung-restricted antibodies can mediate PGD and prevent allo-tolerance. Murine syngeneic (C57BL/6) or allogeneic (C57BL/6 to BALB/c) left lung transplantation model was used. Rabbit polyclonal antibodies were produced against KAT and Col-V and injected pre-transplantation. T-cell frequency was analyzed using ELISPOT while alloantibodies determined using flow-cytometry. Wet-dry ratio, arterial oxygenation and histology were used to determine PGD. Pre-existing Col-V or KAT, but not isotype control, antibodies lead to dose-dependent development of PGD following syngeneic lung transplantation, as evident 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 induce Col-V or KAT specific cellular or humoral immunity. Additionally, none of the mice developed immunity against a non-lung antigen, collagen type II. Pre-existing lung-restricted antibodies, but not isotype control, prevented development of allo-tolerance using MR1 and CTL4-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 pre-existing lung-restricted antibodies might reduce PGD following lung transplantation.