Figure 2. DCreg cells educated on lung stroma inhibit proliferative response of T cells specific to mycobacterial antigens.

(A) - Addition of DCreg to co-cultures of T cell lines with APC suppresses antigen-specific proliferation in the dose-dependent manner (mean triplicate CFU counts ± SD from 4 independent experiments, ~90 per cent inhibition of proliferation by 20 x 10³ cells, ~40 per cent inhibition by 5 x 10³ cells, P < 0.001 and P < 0.01, respectively, compared to positive control). (B) - Suppressive capacity does not depend upon the admixture of other cell types since CD11b⁺ DCreg isolated by magnetic sorting (>95% purity) retain full inhibitory properties (mean triplicate CFU counts ± SD from 2 independent experiments, P < 0.001 and P < 0.01 for two doses of DCreg, ANOVA). (C) - Co-culture with lung stroma is requisite for acquisition of suppressive activity: total BMC, sorted CD11b^b BMC and freshly isolated lin^- cells did not inhibit T cell proliferation (mean triplicate CFU counts ± SD from 2 independent experiments, P > 0.3).