Age‐Related Changes in CCR9+ Circulating Lymphocytes: Are CCR9+ Naive T Cells Recent Thymic Emigrants?

The chemokine receptor CCR9 is reported to be predominantly expressed by thymocytes as well as by circulating gut‐homing and resident T cells in the small intestinal mucosa. Its ligand thymus‐expressed chemokine (TECK) is produced by thymic and small intestinal epithelium. Here we report that the pr...

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Bibliographic Details
Published in:Scandinavian journal of immunology 2001-11, Vol.54 (5), p.435-439
Main Authors: Olaussen, R. W., Farstad, I. N., Brandtzaeg, P., Rugtveit, J.
Format: Article
Language:English
Subjects:
Adolescent
Adult
Aged
Aging - immunology
CD3 Complex - metabolism
CD4-Positive T-Lymphocytes - immunology
Cell Movement
Child
Child, Preschool
Flow Cytometry
Humans
Infant
Infant, Newborn
Leukocyte Common Antigens - metabolism
Middle Aged
Receptors, CCR
Receptors, Chemokine - metabolism
T-Lymphocyte Subsets - immunology
Thymectomy
Thymus Gland - cytology
Thymus Gland - immunology
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Summary:The chemokine receptor CCR9 is reported to be predominantly expressed by thymocytes as well as by circulating gut‐homing and resident T cells in the small intestinal mucosa. Its ligand thymus‐expressed chemokine (TECK) is produced by thymic and small intestinal epithelium. Here we report that the proportion of circulating CCR9+ naive T cells (mostly CD4+) declines with age, from approximately 15% of all T cells at birth to around 1% in adults. The proportion of CCR9+ T cells lacking the classical gut‐homing receptor α4β7, was much higher in children than in adults. Therefore, circulating CD3+CCR9+CD45RA+ cells have most likely left the thymus quite recently. This notion was supported by the small number of CCR9+ naive T cells which was present shortly after thymectomy. Establishing a phenotypic marker for recent thymic emigrants might provide a powerful tool in the clinical assessment and follow‐up after cancer chemotherapy, hematopoietic stem cell transplantation, and during antiretroviral treatment of human immunodeficiency virus (HIV)‐infected patients.
ISSN:0300-9475
1365-3083
DOI:10.1046/j.1365-3083.2001.01008.x