Severe Acute Cellular Rejection With High-Grade Lymphocytic Bronchiolitis Following Transition from Tacrolimus to Belatacept in a Lung Transplantation Recipient: A Case Report

•There has been growing interest in conversion from maintenance calcineurin inhibitors to belatacept—a selective T-cell costimulation antagonist—in lung transplant recipients with chronic kidney disease.•We report a case of A4B2 rejection with acute fibrinous and organizing pneumonia shortly after transitioning to a tacrolimus-free regimen using belatacept. This case report describes a lung transplantation recipient who developed severe acute cellular rejection with high-grade lymphocytic bronchiolitis after transition to a calcineurin-free regimen using belatacept. A 53-year-old man who had undergone lung transplantation 3 years prior developed progressive chronic kidney disease related to tacrolimus. He was transitioned off tacrolimus to belatacept to prevent the need for dialysis. He was admitted 2 months later with acute hypoxemic respiratory failure. Video-assisted thoracic surgery biopsy showed acute fibrinous and organizing pneumonia and A4B2 rejection. He subsequently developed chronic lung allograft dysfunction. This case illustrates the potential increased risk of acute rejection associated with belatacept maintenance immunosuppression.