T helper (Th) 2 cells selectively express IL-21 in addition to the classic Th2 cytokines IL-4, IL-5, and IL-13. In contrast to these clustered Th2 cell cytokine genes, the IL-21 gene resides on a different chromosome and is not coordinately regulated by the same locus control region that directs the expression of other Th2 cytokines. We demonstrate that the proximal promoter of IL-21 controls i...

IL-21 exerts pleiotrophic immunomodulatory activities on a variety of target cells including B cells that undergo class switch recombination (CSR) to IgE. In this study, we examined whether IgE-mediated systemic anaphylaxis was controlled by in vivo administration of IL-21 using the peanut allergy model in mice and investigated the molecular mechanisms underlying the IL-21-induced regulation of...

Interleukin (IL)-21-producing CD4(+)T cells are central to humoral immunity. Deciphering the signals that induce IL-21 production in CD4(+) T cells and those triggered by IL-21 in B cells are, therefore, of importance for understanding the generation of antibody (Ab) responses. Here, we show that IL-6 increased IL-21 production by human CD4(+) T cells, particularly in those that express the tra...

IL-21, a recently identified member of the common gamma-chain (gammac) receptor cytokine family, has been shown to be an important regulator of both innate and adaptive immune responses. In this study, we investigated whether IL-21 could synergize with another gammac cytokine, IL-7, to induce enhanced proliferation and effector function of tumor antigen-specific CD8(+) T cells. Our results show...

Interleukin 21 (IL-21) is a newly described cytokine with homology to IL-4 and IL-15. They belong to a cytokine family that uses the common gamma chain for signaling but also have their private high-affinity receptors. Since it is well known that IL-4 modulates differentiation and activation of dendritic cells (DCs), we analyzed effects of IL-21 compared with IL-15 on DC differentiation, matura...

The aim of the present study was to investigate the role of interleukin (IL)-21 in chronic hepatitis B virus (HBV) infection. IL-21 stimulates T and B cell responses and plays a role in the control of chronic viral infections. Serum IL-21 levels were measured by enzyme immunoassay in 109 patients with chronic HBV infection at various clinical stages, as well as in 19 healthy controls (HCs). The...

Interleukin-2 (IL-2) and IL-21 share activities in the control of T- and B-cell maturation, proliferation, function, and survival. However, opposing roles for IL-2 and IL-21 have been reported in the development of regulatory T cells. To dissect unique, redundant, and opposing activities of IL-2 and IL-21, we compared T- and B-cell development and function in mice lacking both IL-2 receptor α (...

IL-6 is a multifunctional proinflammatory cytokine that is elevated in the serum of patients with pulmonary arterial hypertension (PAH) and can predict the survival of patients with idiopathic PAH (IPAH). Previous animal experiments and clinical human studies indicate that IL-6 is important in PAH; however, the molecular mechanisms of IL-6-mediated pathogenesis of PAH have been elusive. Here we...