The Fas ligand is predominantly expressed in activated T lymphocytes and is
one of the major effector molecules of cytotoxic T lymphocytes and natural
killer cells. Previously, we found excessive apoptosis of epithelial cells
and infiltrating lymphocytes expressing Fas ligand mRNA in the lung tissue
of bleomycin-induced pulmonary fibrosis in mice. Here we demonstrated that
the administration of a soluble form of Fas antigen or anti-Fas ligand ant
ibody prevented the development of this model and that lpr and gld mice wer
e resistant against the induction of pneumopathy. These results suggest tha
t the Fas-Fas ligand pathway plays an essential role in the development of
pulmonary fibrosis and that preventing this pathway could have therapeutic
value in lung injury and fibrosis.