Analysis of Fas system in pulmonary injury of graft-versus-host disease after rat intestinal transplantation.

The lung is one of the primary targets of acute graft-versus-host disease (GVHD), which is the principal complication that occurs after allogeneic intestinal transplantation. The purpose of this study is to investigate the involvement of Fas/Fas ligand system in pulmonary injury after rat semi-allogeneic intestinal transplantation. The lungs mere serially harvested from LEW x BN F1(LBNF1) recipients of either LEW heterotopic intestinal allografts or LBNF1 isografts, on days 1, 3, 5, 9, and 13 posttransplant. In light microscopy, pulmonary injury became apparent on day 13 in the allogeneic combination, showing a thickening of the alveolar septa, The incidence of apoptosis, examined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) biotin nick end-labeling, was observed to increase steadily in the alveolar cells accompanied by a progression of GVHD, In an immunohistochemical study, Fas was constitutively expressed in the lung, although Fas ligand was expressed most extensively on day 9, The immunoreactivity of both Fas and Fas ligand mere observed in alveolar cells, in addition to leukocytes, An analysis by reverse transcription polymerase chain reaction also revealed that the expression of Fas mRNA mas constitutive without any significant change, although that of Fas ligand mRNA increased substantially and peaked on day 9, which was significant compared to the isogeneic combination. In conclusion, transcriptionally up-regulated Fas ligand and increased number of apoptosis suggests that the Fas system may play a role in the pathophysiology of GVHD-induced pulmonary injury.