Th2 and Th9 responses in patients with chronic mucocutaneous candidiasis and hyper-IgE syndrome.

Background: STAT1 mutations cause chronic mucocutaneous candidiasis (CMC), while STAT3 mutations cause hyper-IgE syndrome (HIES). CMC and HIES patients have T helper (Th) 17 defects suffering from mucosal Candida infections, but only patients with HIES show an allergic phenotype with eczema, eosinophilia and high IgE levels.

Objective: We investigated whether differential Th2 and Th9 responses may explain the clinical differences.

Methods: Peripheral blood mononuclear cells of patients with CMC (n = 4), patients with HIES (n = 4), patients with atopic dermatitis (n = 4) and healthy volunteers (n = 13) were stimulated with Candida and Staphylococcus aureus, with and without IL-4. The cytokines IL-5, IL-13, IL-9, IL-17 and TGFβ and regulatory T cells were measured in cell culture supernatants by ELISA or flow cytometry, respectively.

Results: Peripheral blood mononuclear cells of patients with CMC showed a significantly impaired production of the Th2 cytokines IL-5 and IL-13, especially in the presence of IL-4. Moreover, IL-9 production was significantly lower in patients with CMC compared to healthy controls. In contrast, patients with HIES and patients with AD showed normal IL-5 and IL-13 production, while IL-9 production was significantly lower in patients with HIES compared to healthy controls. Although TGFβ was involved in the IL-4-induced IL-9 production, TGFβ levels and the frequency of regulatory T cells did not differ between patients with HIES and controls. Flow cytometry analysis demonstrated an IL-9 IL-17 CD4 subset in healthy controls after stimulation with Candida which was less present in patients with HIES.

Conclusion: Patients with CMC have a general Th defect including Th2 and Th9, while patients with HIES have normal Th2 cytokines. These differences are in line with their clinical presentation. Surprisingly, the allergic cytokine IL-9 was deficient in both HIES and CMC, suggesting a Th-17-derived origin.