Increased circulating Th17 frequencies and serum IL-22 levels in patients with acute generalized exanthematous pustulosis

Background/Objective Acute generalized exanthematous pustulosis (AGEP) is a diffuse pustular disorder that usually begins in intertriginous folds with widespread erythema. The causes in the majority of the cases are drugs. T cells and interleukin (IL)-8 play roles in the development of AGEP, but the mechanism remains to be elucidated. We investigated the involvement of Th17 cells and their cytokine IL-22 in the pathogenesis. Methods Three patients with AGEP were enrolled in this study. The percentages of IL-17+ Th17 cells, interferon gamma+ T cells and IL-4+ T cells were measured in the patients' peripheral blood lymphocytes by intracellular cytokine staining and flow cytometry. The concentration of IL-22 in the sera was measured by enzyme-linked immunosorbent assay. Results The percentages of Th17 cells were markedly higher in all three patients than healthy control individuals. The frequencies of interferon gamma+ T cells were slightly high in the patients compared with the control, and there was no definite tendency in IL-4+ T-cell frequencies. The concentration of IL-22 was remarkably high in all patients when compared with normal subjects with levels under detection. Conclusion Th17 cells and their produced cytokine IL-22 were elevated in the peripheral blood of patients with AGEP. As IL-17 and IL-22 cooperatively stimulate keratinocytes to produce IL-8, IL-8 may contribute to the accumulation of neutrophils in the lesional epidermis of AGEP.