Lung epithelial cells and type II pneumocytes of donor origin after allogeneic hematopoietic stem cell transplantation

Background. In the present investigation, we determined whether donor epithelial lung cells might be detected after allogeneic hematopoietic stem cell transplantation (HSCT). Methods. Lung-tissue specimens were obtained at autopsy from four female patients, two with male donors, after nonmyeloablative HSCT. Immunohistochemical staining for cytokeratin was used to identify lung epithelial cells. The tissue sections were analyzed for the presence of donor-derived lung epithelial cells with the use of fluorescence in situ hybridization of XY-positive cells. Results. All patients showed almost complete donor chimerism in all cell lineages after HSCT with polymerase chain reaction of minisatellites. In the two positive controls, between 2% and 6% Y-chromosome-positive epithelial lung cells were detected in each section. Surfactant-positive male epithelial cells were also detected, indicating engraftment of type II pneumocytes. In the two negative controls, no Y-chromosome-positive cells were detected. Conclusion. Circulating donor stem cells may differentiate into lung epithelial cells after allogeneic HSCT.