Increased interleukin 5 production in eosinophilic Sézary syndrome: regulation by interferon alfa and interleukin 12.

Abstract

Peripheral eosinophilia occurs in a small subpopulation of patients with cutaneous T-cell lymphoma (CTCL) and denotes a poor prognosis. Clinical studies have suggested that the Sézary cell is a T(H)2 type helper T cell that produces cytokines that enhance the differentiation and activation of eosinophils. Interferon alfa (IFN-alpha) and interleukin 12 are effective therapeutic agents for CTCL and other hematologic disorders. Our purpose was to determine the inhibitory activity of IFN-alpha and IL-12 on IL-5 production in vitro by peripheral blood mononuclear cells (PBMCs) obtained from patients with CTCL and eosinophilia. Suppression of IL-5 production by IFN-alpha and IL-12 was assessed by comparing IL-5 production by PBMCs from patients with Sézary syndrome and eosinophilia when cultured alone or in the presence of either IFN-alpha or IL-12. A marked increase in IL-5 production by PBMCs from patients with Sézary syndrome and eosinophilia was observed. IL-5 production was markedly reduced when PBMCs were exposed to IFN-alpha or IL-12. These results suggest that IFN-alpha and perhaps IL-12 may produce a therapeutic response in patients with CTCL and eosinophilia through direct suppression of IL-5 production by malignant Sézary cells.