Altered IL-21 secretion by IL-12Rβ1–deficient CD4⁺ T cells. (A) Intracytoplasmic cytokine expression by naïve and memory CD4⁺ T cells from an IL-12Rβ1–deficient subject and healthy subjects after 8-day culture with anti-CD3/CD28 and either IL-12 or CD40L-stimulated DC supernatant. (B) Cytokine secretion from PBMCs stimulated for 48 hours with SEB. Mann-Whitney test. Control subjects (blue), n = 65; IL-12Rβ1–deficient subjects (orange), n = 17. (C) Associations between IL-6 concentrations and IL-21 concentrations in culture supernatant of PBMCs stimulated with SEB. (D) Contribution of IL-12 in IL-21 secretion. An (left) IL-12p70 blocking antibody or (right) IL-12 (10 ng/ml) was added to the PBMC cultures with SEB. Paired Student t test. Control subjects (blue), n = 16; IL-12Rβ1–deficient subjects (orange), n = 8.