SKIN(2TM) ZK1300 is a three-dimensional human skin model consisting of multilayered dermal fibroblasts and well-differentiated epidermal keratinocyte layers, including a stratum corneum. To characterize this model better, constitutive levels of cytokine gene expression were determined. Reverse transcriptase-polymerase chain reaction (RT-PCR), followed by liquid hybridization to labelled internal probes, demonstrated that interleukin (IL)-1I, IL-1beta, IL-6, IL-8, IL-10, tumour necrosis factor (TNF)I, granulocyte macrophage-colony stimulating factor (GM-CSF), transforming growth factor (TGFbeta1) and IL-12 p35-mRNAs were constitutively expressed whereas IL-12 p40 was not. The contribution of the dermal component of this human skin model (Model ZK1100) was further characterized by determining constitutive cytokines expressed and their modulation by phorbol 12-myristate, 13-acetate (PMA). The dermal component, consisting of multilayered human dermal fibroblasts, constitutively expressed message for IL-1I, IL-1beta, IL-6, IL-8, TGFbeta1, GM-CSF and IL-12 p35. Message was not detected for IL-10, TNFI or IL-12 p40. PMA treatment of the multilayered dermal fibroblasts increased steady-state mRNA levels of IL-1I, IL-1beta, IL-6, IL-8, GM-CSF and TGFbeta1, but did not induce IL-10, TNFI or IL-12 p40 expression at the dose and times tested. In summary, these studies demonstrate that the SKIN(2TM) three-dimensional human skin cultures, and their dermal component, constitutively express mRNA for an array of inflammatory and immunomodulatory cytokines, and that PMA exposure modulates mRNA levels of the dermal cytokines.