Perfusatory recovery of the grafted lung during convalescence from acute rejection

The aim of this study was to evaluate whether or not perfusatory recovery of the grafted lung occurs is the early stage of convalesce from acute rejection following a single lung transplantation. Eight adult mongrel dogs underwent an allotransplantation of the left lung with treatment of 10 mg/kg cyclosporine and 4 mg/kg azathioprine. Doppler flow probes were placed to the ascending aorta and the left pulmonary artery. Immunosuppressant therapy was discontinued to induce rejection after postoperative day 14. When the left pulmonary artery flow rate (l-PAFR) decreased to less than 20%, methylprednisolone (20 mg/kg) was administered for 3 days along with a resumption of cyclosporine and azathioprine. Pulmonary circulation and chest roentgenograms were evaluated every day through the rejection episode. An open lung biopsy was also performed in each dog to obtain specimens of the grafts and native lungs for histologic examination. When l-PAFR decreased to less than 20%, mild acute rejection was found in all dogs. l-PAFR increased significantly on the third day after methylprednisolone treatment. Thereafter, a histologic examination revealed minimal acute rejection in one dog and no abnormality in seven dogs. The perfusatory recovery of the grafted lung was thought to reflect the histological change in the course of convalescence.