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 γ(+) 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 γ(+) 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.