{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T16:22:43Z","timestamp":1791390163135,"version":"4.3.3"},"reference-count":23,"publisher":"Oxford University Press (OUP)","issue":"3","license":[{"start":{"date-parts":[[2006,7,12]],"date-time":"2006-07-12T00:00:00Z","timestamp":1152662400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/journals\/pages\/open_access\/funder_policies\/chorus\/standard_publication_model"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2006,7,12]]},"abstract":"<jats:title>Summary<\/jats:title>\n               <jats:p>Our previous study showed that children who had been partially or completely thymectomized during heart surgery as infants had lower proportions and numbers of total lymphocytes and reduced proportions of T cells (CD3+), helper T cells (CD4+) and naive T cells (CD3+\u2003CD4+\u2003CD45RA+), but normal proportion of cytotoxic T cells (CD8+). In this study T lymphocytes from a selected group of eight of these children and age- and gender-matched controls were characterized further using flow cytometry to determine phenotypes of T cells and T cell subsets related to T cell regulation and phenotypes suggestive of extrathymic maturation. Immune function was assessed by measuring autoantibodies and antibodies against vaccines. The study group had significantly lower numbers of all the main subsets of T lymphocytes and the composition was different. Thus, the proportions of lymphocytes with the following phenotypes: CD3+, CD2+, CD7+, CD4+, CD62L+, CD4+\u2003CD62L+\u2003and CD4+\u2003CD69\u2013 were significantly reduced in the study group compared with the control group, but significantly higher proportions were seen of lymphocytes expressing CD8\u03b1+\u2003CD8\u03b2\u2013 and TCR\u03b3\u03b4+ CD8\u03b1+\u2003CD8\u03b2\u2013. The absolute number and proportion of CD4+\u2003CD25+ cells were reduced but the proportions of the subgroup of naive regulatory T cells (CD4+\u2003CD25+\u2003CD62L+) and non-activated regulatory T cells (CD4+\u2003CD25+\u2003CD69\u2013) were not reduced in the thymectomized children. We conclude that the phenotypic characteristics of T lymphocytes of children who have lost their thymus in infancy are indicative of extrathymic maturation. T regulatory cells appear to be less affected than other subsets by the general reduction in T cell numbers.<\/jats:p>","DOI":"10.1111\/j.1365-2249.2006.03139.x","type":"journal-article","created":{"date-parts":[[2006,7,12]],"date-time":"2006-07-12T09:16:53Z","timestamp":1152695813000},"page":"407-412","source":"Crossref","is-referenced-by-count":44,"title":["Evidence for extrathymic T cell maturation after thymectomy in infancy"],"prefix":"10.1093","volume":"145","author":[{"given":"H","family":"Torfadottir","sequence":"first","affiliation":[{"name":"Faculty of Medicine, University of Iceland, Reykjavik, Iceland"},{"name":"Lyfjathroun hf-Biopharmaceuticals, Reykjavik, Iceland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J","family":"Freysdottir","sequence":"additional","affiliation":[{"name":"Lyfjathroun hf-Biopharmaceuticals, Reykjavik, Iceland"},{"name":"Centre for Rheumatology Research, Iceland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"I","family":"Skaftadottir","sequence":"additional","affiliation":[{"name":"Department of Immunology, Iceland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A","family":"Haraldsson","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, University of Iceland, Reykjavik, Iceland"},{"name":"Children\u2019s Hospital Iceland, Landspitali University Hospital, Reykjavik, Iceland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G","family":"Sigfusson","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, University of Iceland, Reykjavik, Iceland"},{"name":"Children\u2019s Hospital Iceland, Landspitali University Hospital, Reykjavik, Iceland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"H M","family":"Ogmundsdottir","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, University of Iceland, Reykjavik, Iceland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2006,7,12]]},"reference":[{"key":"2022010506232245100_b1","volume-title":"Immunobiology: the immune system in health and disease","author":"Janeway","year":"2001","edition":"5th edn"},{"key":"2022010506232245100_b2","doi-asserted-by":"crossref","first-page":"1583","DOI":"10.1084\/jem.172.6.1583","article-title":"Lineage relationships and developmental kinetics of immature thymocytes. 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