Patients with primary immunodeficiency caused by IL21R or IL21 mutations have been described 6 – 9, and their phenotypes have provided invaluable insights into the role of IL-21 in host defense.

A recent study reported that homozygous loss-of-function mutations in the IL21R gene cause a primary immunodeficiency in humans, resulting in recurrent respiratory and gastrointestinal cryptosporidium infections, and chronic liver disease.

IL-21, the most recently discovered member of the IL-2 cytokine family, is an attractive subject for research due to its involvement in experimental models of autoimmunity, its ability to down-regulate IgE production, and its anti-tumor properties. Its interest for cancer immunotherapy stems from its physiological immune-enhancing functions.

Mar 23, 2015 · However, the most convincing evidence for the criticality of IL-21 is the discovery of humans with loss-of function mutations in IL21 or IL21R who develop severe immune dysregulation, characterized by infectious susceptibility to opportunistic pathogens and, paradoxically, autoimmunity.

Apr 22, 2014 · IL-21 has a key role in B cell differentiation to plasma cells and in the development of T follicular helper cells, promoting functional germinal centres and immunoglobulin production. IL-21...

Interleukin 21 (IL-21) is a protein that in humans is encoded by the IL21 gene. [5][6][7] Interleukin-21 is a cytokine that has potent regulatory effects on cells of the immune system, including natural killer (NK) cells and cytotoxic T cells that can destroy virally infected or cancerous cells. [5][8] This cytokine induces cell division ...

Feb 26, 2016 · Recent reports describing patients with primary immunodeficiency caused by mutations of IL21 or IL21R have further deepened our knowledge of the role of this cytokine in host defense.

Dec 1, 2003 · IL-21 is a recently described type I cytokine produced by activated CD4 + T cells that profoundly affects the growth, survival, and functional activation of B, T, and natural killer lymphocytes in concert with other cytokines or activating stimuli.

Biallelic inactivating mutations in IL21R causes a combined immunodeficiency that is often complicated by cryptosporidium infections.

To clarify the molecular basis of IL-21 actions, we investigated the role of tyrosine residues in the IL-21R cytoplasmic domain. Simultaneous mutation of all 6 tyrosines greatly diminished IL-21–mediated proliferation, whereas retention of tyrosine 510 (Y510) allowed full proliferation.