Human thymus regeneration and T cell reconstitution.
The thymus supports the development of T cells throughout life from hematopoietic progenitor cells migrating from the bone marrow. During the early years after birth thymic activity is highest, but progressively declines resulting in diminished naïve T cell output. Underlying causes of thymic involution may be degeneration of the stromal thymic network, providing survival and differentiation factors for developing T cells, or insufficiency of the progenitor cells to home and/or develop in the aged thymus. In young people the reduced thymic output is insignificant, since the peripheral T cell compartment is under compensatory homeostatic control. However, in more or less immunocompromised individuals, including aged people and patients depleted of T cells due to conditioning regimens before bone marrow transplantation or HIV infection, the thymus is necessary to replenish the peripheral T cell compartment. This may require rejuvenation of the thymus. Alternatively, approaches to generate mature T cells independent of the thymus have gained considerable interest.
Legrand
Nicolas
N
Department of Cell Biology & Histology, Academic Medical Center at the University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands.
Dontje
Wendy
W
van Lent
Anja U
AU
Spits
Hergen
H
Blom
Bianca
B
D000818:Animals; D016026:Bone Marrow Transplantation / Q000009:adverse effects; D006412:Hematopoietic Stem Cells / Q000502:physiology; D006801:Humans; D016219:Immunotherapy, Adoptive; D051379:Mice; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D012038:Regeneration; D013601:T-Lymphocytes / Q000502:physiology*; D013950:Thymus Gland / Q000502:physiology*
D011948:Receptors, Antigen, T-Cell