Insights into thymic aging and regeneration

The deterioration of the immune system with progressive aging is believed to contribute to morbidity and mortality in elderly humans due to the increased incidence of infection, autoimmunity, and cancer. Dysregulation of T‐cell function is thought to play a critical part in these processes. One of t...

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Bibliographic Details
Published in:Immunological reviews 2005-06, Vol.205 (1), p.72-93
Main Authors: Taub, Dennis D., Longo, Dan L.
Format: Article
Language:English
Subjects:
Adipocytes - cytology
Adipocytes - metabolism
Aging - immunology
Aging - pathology
Animals
Gene Expression Profiling
Humans
Regeneration - drug effects
T-Lymphocytes - cytology
T-Lymphocytes - immunology
Thymus Gland - cytology
Thymus Gland - growth & development
Thymus Gland - immunology
Thymus Gland - pathology
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Summary:The deterioration of the immune system with progressive aging is believed to contribute to morbidity and mortality in elderly humans due to the increased incidence of infection, autoimmunity, and cancer. Dysregulation of T‐cell function is thought to play a critical part in these processes. One of the consequences of an aging immune system is the process termed thymic involution, where the thymus undergoes a progressive reduction in size due to profound changes in its anatomy associated with loss of thymic epithelial cells and a decrease in thymopoiesis. This decline in the output of newly developed T cells results in diminished numbers of circulating naïve T cells and impaired cell‐mediated immunity. A number of theories have been forwarded to explain this ‘thymic menopause’ including the possible loss of thymic progenitors or epithelial cells, a diminished capacity to rearrange T‐cell receptor genes and alterations in the production of growth factors and hormones. Although to date no interventions fully restore thymic function in the aging host, systemic administration of various cytokines and hormones or bone marrow transplantation have resulted in increased thymic activity and T‐cell output with age. In this review, we shall examine the current literature on thymic involution and discuss several interventional strategies currently being explored to restore thymic function in elderly subjects.
ISSN:0105-2896
1600-065X
DOI:10.1111/j.0105-2896.2005.00275.x