TYK2 deficiency impairs the response to IL-23 but not to IL-27 nor IFN-γ. (A) Western blot analysis of STAT1 (pSTAT1, top) and STAT3 (pSTAT3, bottom) phosphorylation in EBV–B cells from healthy controls (C1 and C2), TYK2-deficient patients (P1 and P2), a patient with complete STAT1 deficiency (STAT1*), and an AD-HIES patient with a heterozygous STAT3 mutation (WT/T708N; STAT3*), after stimulation with 100 ng/ml IL-27 for 20 min. STAT1, STAT3, and α-tubulin levels were also assessed. The results shown are representative of at least two independent experiments. (B) Microarray analysis of HVS–T cell lines from three healthy controls, P2, and an IL-12Rβ1–deficient patient. Cells were stimulated for 12 h with 100 ng/ml IL-23. The difference between nonstimulated and stimulated cultures is shown as a fold change. (C) Western blot depicting phospho-STAT3 (pSTAT3) in EBV–B cells from a healthy control (C, C1, and C2), TYK2-deficient patients (P1, P2, P3, P5, P7, and P8), an AD-HIES patient carrying a heterozygous STAT3 mutation (WT/T708N; STAT3*), an IL-12Rβ1–deficient patient (IL-12Rβ1*), and a STAT1-deficient patient (STAT1*), without (−) and with (+) stimulation for 30 min with 100 ng/ml IL-23. α-Tubulin was used as a protein loading control. The results shown are representative of at least three independent experiments. After analysis by densitometry, a p-value <0.05 (0.0295) for the two-tailed Student’s t test for the comparison of IL-23–stimulated controls and TYK2-deficient patients (TYK2) was found. White lines indicate that intervening lanes have been spliced out. (D) Western blot depicting phospho-STAT3 (pSTAT3) in mock-transduced (left) and TYK2-transduced (right) EBV–B cells from a healthy control and P1, P2, P3, and P5, without (−) and with (+) stimulation for 30 min with 100 ng/ml IL-23. (E) Flow cytometry analysis of blood from TYK2-deficient patients P2 and P4, healthy controls (local controls, LC; and travel controls, TC), STAT3-deficient patients (STAT3*), and IL-12p40– and IL-12Rβ1–deficient patients (IL-12p40* and IL-12Rβ1*), showing the percentage of CD3+ T cells producing IL-17 ex vivo. A p-value <0.05 or <0.001 in two-tailed Student’s t tests is indicated by * or ***, respectively. Mean values for each set of conditions are indicated by solid lines. (F) Responses to IFN-γ (105 IU/ml for 20 min) and IL-27 (100 ng/ml for 20 min) were evaluated by EMSA in EBV–B cells from the TYK2-deficient patients (P1, P2, and P3), two healthy controls (C1 and C2), and a STAT1-deficient patient (STAT1*), with a GAS probe. (G) Flow cytometry analysis to assess the phosphorylation of STAT3 (pSTAT3) in EBV–B cells from two healthy controls (C1 and C2), three TYK2-deficient patients (P1, P2, and P3), and an AD-HIES patient (STAT3*), left untreated (−) or treated with 100 ng/ml IL-21 for 15 min. Intracellular staining was performed with APC-conjugated anti–human pSTAT3 Ab. (H and I) Cytokine production by in vitro–differentiated naive CD4+ T cells from control donors and TYK2-deficient patients (P1, P2, and P4). Naive (CD45RA+CCR7+) CD4+ T cells were purified from the PBMCs of WT controls (n = 6) or TYK2-deficient patients P1, P2, and P4 and cultured for 5 d. Cells were cultured with TAE beads (anti-CD2/CD3/CD28) alone (Th0) or together with polarizing stimuli (TGFβ, IL-1β, IL-6, IL-21, IL-23, anti–IL-4, and anti–IFN-γ) to generate Th17 type cells. After 5 d, culture supernatants were assessed for the secretion of IL-17A or IL-17F with cytometric bead assays. (J) Naive and memory (defined as CD45RA−) CD4+ T cells from WT controls (n = 5) and TYK2-deficient patients (n = 3; P1, P2, and P4) were purified (>98% purity) by FACS and cultured with TAE beads (anti-CD2/CD3/CD28) for 5 d, and the IL-17A+ cells were then assessed by flow cytometry. All error bars indicate SEM.