Samson, Leonard DaniëlEngelfriet, PeterVerschuren, W M MoniquePicavet, H Susan JFerreira, José Ade Zeeuw-Brouwer, Mary-LèneBuisman, Anne-MarieBoots, A Mieke H2023-04-072023-04-072022-01-171742-49333503905510.1186/s12979-021-00261-whttp://hdl.handle.net/10029/626620Elderly often show reduced immune functioning and can develop chronic low-grade inflammation. Why some elderly are more prone to become frail is unknown. We investigated whether frailty is associated with altered cytokine signaling through the JAK-STAT pathway in leukocytes of 34 individuals aged 65-74 years. In addition, we investigated how this relation is affected by chronic low-grade inflammation during the previous 20 years. Cytokine signaling was quantified by measuring intracellular STAT1, STAT3, and STAT5 phosphorylation in monocytes, B cells, CD4+ T cells and CD8+ T cells upon stimulation with IL-2, IL-6, IL-10, IFNα and IFNγ, using phospho-flow cytometry. Presence of chronic low-grade inflammation was investigated by evaluating 18 different plasma inflammatory markers that had been measured repeatedly in the same individuals over the previous 20 years. Frailty was assessed as a score on a frailty index.en© 2021. The Author(s).Chronic low-grade inflammationFrailtyImmune functionImmunosenescenceJAK-STAT pathwayPhospho-flow cytometryArticleImmunity & ageing : I & A