Differential expression of mRNA for Th1 and Th2 cytokine‐associated transcription factors and suppressors of cytokine signalling in peripheral blood mononuclear cells of patients with atopic dermatitis

SUMMARY Atopic dermatitis is characterized by Th2‐dominant immunity. Recently many intracellular molecules have been reported to regulate cytokine expression and T cell differentiation. GATA‐3 and T‐box expressed in T cells (T‐bet) are transcription factors that play a critical role in the development of Th2 and Th1 immunity, respectively. Suppressor of cytokine signalling (SOCS)‐3 and SOCS‐5, are negative regulators of the cytokine signalling induced by IL‐12 and IL‐4, respectively. Txk is a transcription factor that activates IFN‐ γ gene directly. The present study was designed to identify intracellular molecules that are responsible for the pathogenesis and the imbalance of cytokines in atopic dermatitis. Semi‐quantitative RT‐PCR revealed that in peripheral blood mononuclear cells without any stimulation the levels of mRNA for GATA‐3 and SOCS‐3 were elevated, the levels of mRNA for Txk were depressed and the levels of mRNA for T‐bet and SOCS‐5 were comparable in patients with atopic dermatitis as compared with healthy controls. In addition, successful therapy normalized levels of mRNA for GATA‐3 and Txk, although those for the others including IL‐4, IL‐5, IL‐10, IL‐13 and IFN‐ γ did not change. Levels of Txk mRNA correlated with those of IFN‐ γ , while the mRNA levels of the other regulators did not correlate with those of any of the cytokines. These results suggest GATA‐3 and Txk might be involved in skin lesions, while SOCS‐3 might be associated with an imbalance of cytokines that is difficult to normalize in atopic dermatitis.