Interleukin‐21 differentially affects human natural killer cell subsets

Abstract

Summary Interleukin‐21 (IL‐21) is a cytokine with pleiotropic effects on various cell types including dendritic cells, B cells, T cells and natural killer (NK) cells. To evaluate if IL‐21 affects human NK cell subpopulations in a similar fashion, functional studies were performed on CD56dim and CD56bright NK cells, both bearing IL‐21 receptors at identical densities. Stimulation with IL‐21 strongly induced proliferation of CD56bright NK cells and cytotoxicity against K562 target cells was preferentially augmented in CD56dim NK cells. In contrast, stimulation with IL‐2 and IL‐21 alone or in combination failed to induce interferon‐γ and tumour necrosis factor‐α production in the two NK cell subsets. Intracellular analysis of signal transducer and activator of transcription (STAT) proteins revealed that IL‐21 by itself induces phosphorylation of STAT1 and STAT3 in CD56dim NK cells, and to an even higher degree in CD56bright NK cells. In this CD56bright NK cell population alone, IL‐2 weakly phosphorylated STAT1 and STAT3, which was further increased when cells were treated with the combination of both cytokines. In contrast, STAT5 was strongly phosphorylated only in CD56bright NK cells by low‐dose IL‐2, while IL‐21 did not affect STAT5 at all. In summary, we present data indicating that the NK‐cell‐directed cytokines IL‐2 and IL‐21 not only affect functions in NK cell subpopulations differently but can also act additively.

Cytotoxic functions and susceptibility to apoptosis of human CD56bright NK cells differentiated in vitro from CD34+ hematopoietic progenitors

“…Moreover, it has been described that human CD56 bright NK cells and their mouse counterpart, differently from CD56 dim ones, are characterized by the expression of GATA-3 and CD127 (34), suggesting the presence of at least two independent pathways of NK cell differentiation: thymus/lymph node (CD56 bright ) and bone marrow/spleen (CD56 dim ). Consistent with this later hypothesis there are evidences of a substantially different activation pathways (CD56 bright by cytokines, CD56 dim by targets) and thus a different response not only to IL-2 and IL-15 but also to TGFbeta and IL-21 (35)(36)(37). In line with this, our data from cultures with IL-21 show a rapid development of highly cytotoxic CD16 (7,9,18) and, further, that this cytokine inhibits their maturation.…”

CD20+ T cell numbers are decreased in untreated HIV-1 patients and recover after HAART

“…Prior to intracellular staining for cytokine production, cells were stimulated with PMA/ionomycin (5 ng/ml and 500 ng/ml, respectively, Sigma-Aldrich, Munich, Germany) as previously described [11,12]. Briefly, cells were adjusted to 2 × 10 6 PBMC in 1 ml R10, supplemented with PMA/ionomycin and cultured in a humidified incubator at 37 • C. After one hour, brefeldin A (2 g/ml, Sigma-Aldrich, Munich, Germany) was added to inhibit secretion and achieve accumulation of produced cytokines.…”

New aspects of NK cell subset identification and inference of NK cells’ regulatory capacity by assessing functional and genomic profiles

“…In contrast, CD25 was preferentially enhanced on CD56 bright NK cells after stimulation with IL-21 alone. IL-2 induced a decrease of CD25, especially on the CD56 bright NK cell subset (Wendt et al, 2007). This could be due to an internalization of this receptor chain, which might serve as a regulatory feedback mechanism (Duprez et al, 1992;Yu and Malek, 2001).…”

“…In parallel, signalling via IL-21R and IL-2R was traced by intracellular staining of phosphorylated STAT proteins using flow cytometry (Wendt et al, 2007).…”

“…Expression patterns of selected molecules were also determined by using intra-and extra-cellular FACS analyses (Wendt et al, 2006). Results described in this manuscript are mainly based on the publications of Wendt et al (2006Wendt et al ( , 2007 and supplemented with data not yet published.…”