Fig. 4

aPC promotes T_reg expansion and inhibits T-cell reactivity in human T-cells. a Mixed lymphocyte reaction (MLR) of human peripheral blood T-cells (T) with allogenic antigen-presenting cells (AgPC) for 96 h. T-cell reactivity was measured by thymidine incorporation during the final 16 h. Concomitant incubation with aPC (+aPC; 20 nM, every 12 h) reduces T-cell reactivity. b aPC-preincubation (20 nM, 1 h, 37 °C) of human pan T-cells (T(aPC) + AgPC), but not of human AgPC (T + AgPC(aPC)) reduces T-cell reactivity in the MLR in comparison to T_reg-depleted T-cells (T-Tr + AgPC) and T-cells (T + AgPC). c Human pan T-cells without (T) or with (T(aPC)) aPC-preincubation were labelled with eFluor450, stimulated with AgPC, and proliferation was measured on day 1 (D1) and day 4 (D4) by FACS. d, e aPC-preincubation of human pan T-cells reduces the frequency of CD4⁺ T-bet⁺ and CD4⁺ROR-γt⁺ T-cells while increasing CD4⁺FOXP3⁺ T_regs (d). Concomitantly, expression of the pro-inflammatory cytokines IFN-γ, TNF-α, and IL-17A, as measured by flow cytometry after 48 h of MLR, is reduced, while that of IL-10 is increased (e). f TGFβ1 levels in the supernatant of human T-cells MLR, measured after 96 h by ELISA. Results of at least three independent experiments (a, b, and d–f), each containing cells from three different donors, are shown; representative histogram plots c from triplicate wells of three independent experiments are shown; MFI and exemplary FACS images corresponding to Figs. 4d, e are shown in Supplementary Figs. 6 and 7; *P < 0.05, **P < 0.01 (a, d–f: t-test, b ANOVA)