ed. So far, the reliable list of inhibitory mediators is 
limited to IL-10, TGF-, NO and PGE2. Our results are in agreement with previous findings: inhibitory activity of supernatants obtained from DCreg educated on lung stroma partly depended upon the presence of PGE2, and the differences in regulatory activity of DCreg obtained from nave and TB-infected mice of susceptible and resistant strains correlated with the differences in IL-10 and NO production. It was not possible to compare the levels of TGF- in supernatants in our system: expansion of DCreg in cocultures with lung stroma is ineffective in the absence of FCS in culture medium, ELISA results are strongly altered due to the presence of FCS, and qrt-PCR says little about real secretion of the active form of TGF-. In summary, our data demonstrate that the lung stroma educates DC progenitors in such a way that they develop in DCreg able to inhibit mycobacteria-specific T cell proliferation. This ability is apparently important for limiting inflammation caused by M. tuberculosis-triggered disease, which is underlined by the consequence of infection in genetically different mouse strains: during the period of observation instructive capacity was retained by more resistant mice but gradually decreased in TB-susceptible animals. 20-22 days. To examine pathology of the lung tissue, mice were euthanized by the thiopental overdose. Lung tissue was frozen in the regimen 9057848 of -600C to -200C temperature gradient in the electronic Cryotome, and KU55933 web 6-8mthick sections were made across the widest area of the lobe, fixed with acetone and stained with hematoxylin-eosin. Lung stromal cell preparations Lung stroma from 4 donor mice of each strain was obtained in each experiment. Nave or infected B6 and I/St mice were euthanized by injection of the thiopental overdose, and lung cell suspensions were prepared using the methods described earlier. Briefly, blood vessels were washed out and repeated broncho-alveolar lavage was performed using 0.02% EDTA-PBS with antibiotics. Lung tissue was sliced into 1-2 mm3 pieces and incubated at 370C for 90 min in RPMI-1640 containing 5% FCS, antibiotics, 10 mM HEPES, 200 U/ml collagenase and 50 U/ml DNase-I. Single cell suspensions were obtained by vigorous pipetting. Lung cells were washed twice in HBSS containing 2% FCS 19302590 and antibiotics and re-suspended in RPMI-1640 medium supplemented with 10% FCS, 10 mM HEPES, 2 mM L-glutamine, 1% nonessential amino acids, 1 mM pyruvate, 5×10-5 2mercaptoethanol and antibiotics. 20-30 x 106 cells were incubated in 10 ml of medium 1 for 2 h on 90 mm Petri dishes at 370C. Non-adherent cells were removed by triple washing with warm HBSS containing 2% FCS. Adherent cells were detached from plastic by incubating monolayers in 0.02% EDTA-PBS solution for 30 min at room temperature, and after triple washing re-suspended in supplemented RPMI-1640 for further culturing. Materials and Methods Mice of inbred strains I/StSnEgYCit and C57BL/6JCit were bred and maintained under conventional, non-SPF conditions at the Animal Facilities of the Central Institute for Tuberculosis in accordance with guidelines from the Russian Ministry of Health 755, and under the NIH Office of Laboratory Animal Welfare Assurance A5502-11. Water and food were provided ad libitum. Female mice of 8-12 wk of age in the beginning of experiments were used. All experimental procedures were approved by the CIT animal care committee. Purification and culture of progenitor ce