Effect of IFN-γ–treated DCs on anti-CD3 antibody-activated autologous and allogeneic peripheral lymphocytes of healthy donors. Untreated or IFN-γ–treated mDCs generated with CD40L + LPS were coincubated for 3 days with anti-CD3 antibody-stimulated autologous blood lymphocytes at a ratio of 1:10 (n = 7) (A) or at increasing ratios (n = 6) (B). Alternatively, DCs were cocultured for 5 days with allogeneic lymphocytes at a ratio of 1:10 (n = 8) (C) or at increasing ratios (n = 5) (D). Proliferation was assessed by adding [³H]thymidine (1 μCi [0.037 MBq]/well) during the last 18 hours of culture. The positive control consisted of DCs plus anti-CD3 antibody-activated autologous or allogeneic lymphocytes, and the negative control consisted of lymphocytes and DCs alone. Single values represent mean ± SD and are expressed as a percentage of the positive control values (= 100%) (mean stimulation: autologous, 23 000 ± 6000 cpm; allogeneic, 27 800 ± 8000 cpm). The difference between the T-cell stimulatory capacity of native DCs and IDO DCs was statistically not significant in experiment A and borderline significant (P = .026) in experiment C.