['Knowledge of the effect of topically applied calcineurin antagonists such as tacrolimus on the sensitization phase of allergic contact dermatitis is currently limited.', 'To investigate tacrolimus-dependent immunomodulation on gene expression alterations in human antigen-presenting cells which are stimulated with small-molecular-weight contact allergens.', 'Monocyte-derived dendritic cells (moDC) and THP-1 cells were stimulated with the contact sensitizer cinnamic aldehyde (CAld) and compared with the very strong experimental sensitizer 2,4,6-trinitrobenzene sulfonic acid (TNBS) in vitro. Quantitative PCR analysis was used to detect gene expression changes, particularly of interleukin (IL) 8, as an indicator of differential dendritic cell (DC) gene expression after sensitizer stimulation in the absence or presence of tacrolimus and betamethasone at two different concentrations.', 'DC activation was clearly demonstrated by a significant IL-8 upregulation after 24 h, whereas tacrolimus or betamethasone alone did not affect IL-8 baseline expression. Betamethasone and, to a lesser extent, tacrolimus led to a marked reduction of chemical-induced IL-8 expression by TNBS and CAld.'] Does tacrolimus modulate dendritic cell activation in the sensitization phase of allergic contact dermatitis?