Zola, H.Ridings, J.Elliott, S.Nobbs, S.Weedon, H.Wheatland, L.Haslam, R.Roberton, D.Macardle, P.2006-06-232006-06-231998Human Immunology, 1998; 59(10):615-6240198-88591879-1166http://hdl.handle.net/2440/7338IL-2 receptor is expressed at low levels on adult blood lymphocytes, and at lower levels on cord blood cells. IL-2 receptor alpha and beta chain expression increases gradually from 0-18 months of age. The level of soluble CD25 (IL-2 receptor alpha chain) has been reported to be elevated in cord blood. Quantitative RT-PCR showed that adult cells express 10 times as much CD25 mRNA as cord cells. Cord plasma showed only a marginal ability to strip CD25 from the membrane. To assess the functional consequences of low IL-2 receptor expression, cord and adult cells were activated in vitro. The response was stimulus-dependent, but cord cells upregulated CD25 readily. Cord and adult cells proliferated in an IL-2-dependent assay to a similar extent. Infants suffering acute infection showed marginally higher levels of membrane CD25 expression than infants without overt infection. Thus neonatal and infant lymphocytes express lower levels of IL-2 receptors than adult cells, reflecting lower mRNA concentrations at least for CD25; they are able to up-regulate receptors in response to in vitro stimulation and are able to respond in vitro to IL-2-dependent stimulation; however in vivo there may be a dampening down of the IL-2 system in infancy.enLeukocytes, MononuclearFetal BloodHumansCommunicable DiseasesReceptors, Interleukin-2RNA, MessengerInterleukin-2Lymphocyte ActivationAge FactorsDown-RegulationUp-RegulationAdultInfantInfant, NewbornInfectionsJournal article0030005608001998099510.1016/S0198-8859(98)00069-X2-s2.0-003175150369614