Cytokine with immunoregulatory activity. May promote the transition between innate and adaptive immunity. Induces the production of IgG1 and IgG3 in B-cells (By similarity). May play a role in proliferation and maturation of natural killer (NK) cells in synergy with IL15. May regulate proliferation of mature B- and T-cells in response to activating stimuli. In synergy with IL15 and IL18 stimulates interferon gamma production in T-cells and NK cells. During T-cell mediated immune response may inhibit dendritic cells (DC) activation and maturation.
[1]"Early-onset inflammatory bowel disease and common variable immunodeficiency-like disease caused by IL-21 deficiency."Salzer E., Kansu A., Sic H., Majek P., Ikinciogullari A., Dogu F.E., Prengemann N.K., Santos-Valente E., Pickl W.F., Bilic I., Ban S.A., Kuloglu Z., Demir A.M., Ensari A., Colinge J., Rizzi M., Eibel H., Boztug K.J. Allergy Clin. Immunol. 133:1651-1660(2014). [2]"Crystal structure of interleukin-21 receptor (IL-21R) bound to IL-21 reveals that sugar chain interacting with WSXWS motif is integral part of IL-21R." Hamming O.J., Kang L., Svensson A., Karlsen J.L., Rahbek-Nielsen H., Paludan S.R., Hjorth S.A., Bondensgaard K., Hartmann R.J. Biol. Chem. 287:9454-9460(2012). [3]"The existence of multiple conformers of interleukin-21 directs engineering of a superpotent analogue."Bondensgaard K., Breinholt J., Madsen D., Omkvist D.H., Kang L., Worsaae A., Becker P., Schioedt C.B., Hjorth S.A.J. Biol. Chem. 282:23326-23336(2007).
