Lung transplantation complicated by graft-versus-host disease and confounded by incidental transfusion-associated macrochimerism.

Background: Passenger lymphocyte-mediated graft-versus-host disease (GVHD) in solid organ transplantation (SOT-GVHD) is considered a rare complication, particularly among recipients of lung allografts. The risk of transfusion-associated GVHD (TA-GVHD) in solid organ transplants is also considered rare. The suspicion of either may be heralded by signs and symptoms of GVHD in the company of a population of passenger lymphocytes in excess of 1 percent (microchimerism). This case report illustrates the challenge of a patient who presented with macrochimerism both from the lung transplant allograft and from transfusions.

Methods: Chimerism assessments of the pre- and posttransplant donor lung, and the recipient's aplastic marrow, were made using DNA-based polymerase chain reaction testing.

Results: Macrochimerism was observed in both the posttransplant aplastic host marrow and the engrafted donor lung, with the former predominantly consisting of lung donor lymphocytes and the latter a mixture of lung and presumably transfusion source donor lymphocytes. The pretransplant donor lung exhibited no GVHD-like pathology.

Conclusions: This case demonstrates SOT-GVHD, with the unusual feature of concomitant macrochimerism from transfusions. SOT-GVHD likely predisposed this patient to the observed transfusion-associated macrochimerism. However, the dissociation between transfusion-attributable macrochimerism and attributable pathology is intriguing. Furthermore, the risk spectrum of transfusion-associated macrochimerism and TA-GVHD in solid organ transplant recipients with and without the complication of SOT-GVHD is unknown and warrants further study.