Host-derived nitric oxide synthase and IDO do not contribute to IPS. (A) iNOS, eNOS, and IDO transcript levels were determined by real-time PCR in lungs from wt and IFNγR−/− recipients of allogeneic Balb/c grafts 3 days after SCT. Results normalized to β2 microglobulin and expressed as means ± SE of duplicates from individual animals (n = 3 per group). (B) Semiquantitative lung histology in wt and iNOS−/− recipients or wt and eNOS−/− recipients of Balb/c grafts 9 days after SCT (n = 8 per group). Non-GVHD controls received TCD grafts (n = 4). A cohort of wt recipients of allogeneic T-cell–replete grafts were implanted with slow release pellets containing the IDO inhibitor 1-MT or vehicle as described in “Materials and methods” (n = 9 per group). Non-GVHD controls received TCD grafts in conjunction with slow release pellets containing 1-MT (n = 3). ND indicates no pathology detected. Data expressed as means plus or minus SE of individual animals, combined from 2 experiments. (C) Representative hematoxylin and eosin–stained images of lung venules from wt and IFNγR−/− recipients given transplants of T-cell–replete grafts demonstrating leukocyte adhesion and migration across the endothelium in the IFNγR−/− recipients (400 ×). (D) Quantitative analysis of leukocyte adhesion and transmigration within lung venules in wt and IFNγR−/− recipients of T-cell–replete or TCD grafts (n = 5-6 per group). Data are means plus or minus SE of individual animals where the mean number of adherent and transmigrating leukocytes was determined in 10 venules per lung. **P < .01, wt versus IFNγR−/− recipients. (E) Purified donor (H-2Dd+) CD4+ T cells were sort-purified (> 95%) from the lungs of wt (□) or IFNγR−/− (■) recipients and restimulated with purified allogeneic DCs. Proliferation was determined by 3H incorporation 60 hours later and IFNγ, IL-5, and IL-4 were measured in supernatants by cytokine bead array. Data are means plus or minus SE of triplicate wells and is 1 of 2 replicate experiments. ND indicates not detected.
