Figure 1.

Intracellular free zinc level substantially increased in allogeneic activated regulatory T cells (Tregs). (a,b) Whole blood was taken from healthy volunteers and parameters were measured directly without delay or separation. (a) Non-activated whole blood samples were analyzed regarding cellular percentage of CD4⁺CD25⁺ and CD4⁺FOXP3⁺ expressing Tregs. (b) Intracellular free zinc level is displayed for CD4⁺CD25⁺ Tregs and CD4⁺CD25^neg T cells. (c,d) 2 × 10⁶ peripheral blood mononuclear cells (PBMCs)/mL were pre-incubated with 50 µM zinc (15 min) or remained untreated. Subsequently, mixed lymphocyte cultures (MLCs) were generated for 15 min, 60 min, and five days. (c) Measurement of the free intracellular zinc level was performed by Fluozin3-AM in gated Th cell populations: CD4⁺CD25^low T cells (white bars) and CD4⁺CD25^hi T cells (grey bars). (d) Activated (CD4⁺CD69⁺) Th cells in PBMCs and MLCs are displayed. (⁺: positive, expression, ^low: low expression, ^hi: high expression, ^neg: negative, no expression) All data are shown as means + SEM (standard error of mean) of n = 4–6 independent experiments (* p < 0.05, Student’s t-test).