Table 1

Parameters of T-cell homeostasis in humans

T-cell population


CD4+ naive

CD4+ memory

CD8+ naive*

CD8+ memory*


Pool size (n)

~ 1 × 1011

~ 1 × 1011

~ 5 × 1010

~ 5 × 1010

Diversity

(2–20) × 106 TCR β-chains, each paired with > 25 α-chains [3,4]

(2–20) × 105 TCR β-chains, each paired with 1–2 α-chains [3,4]

Not determined

Not determined

Oligoclonality

None

Infrequent

None

Frequent in the elderly

Frequency of Ki67+ T cells (%)

~ 0.2

1–2

~ 0.3

~ 3

Daily replacement rate by stable isotope labeling of DNA (%)

~ 0.1 [25]

~ 0.8 [87]

~ 0.1 [25]

~ 0.9 [87]

Half-life (days)

~ 700

~ 80

~ 700

~ 70

Daily production rates (n)

1.5 × 108

1.5 × 109

0.8 × 108

0.8 × 109


* Phenotypic distinction imperfect. Data from [3] for total T cells.

Goronzy and Weyand Arthritis Res Ther 2003 5:225-234   doi:10.1186/ar974