We observed that the depletion of Gr-1+ myeloid cells prevented the resolution of bleomycin-induced pulmonary fibrosis, whereas their mobilization from the bone marrow or the adoptive transfer of isolated Gr-1+ myeloid cells either prior to or after bleomycin challenge enhanced the rate of fibrotic resolution in this model via the TRAIL-dependent apoptosis of myofibroblasts. The gene discussed is TNFSF10; the disease is pulmonary fibrosis.