B-cell kinetics in humans: rapid turnover of peripheral blood memory cells.
Level 4 - case-series / case-control
In vivo human kinetic physiological study / case-series without randomized comparison
PubMed 15644412 · doi:10.1182/blood-2004-09-3740
What was done
Human subjects (young adults and elderly) underwent in vivo labeling of dividing cells using 6,6-(2)H(2)-glucose. Peripheral blood B lymphocytes were isolated and sorted into total, naive, and memory subsets based on CD27 expression using monoclonal antibodies, followed by gas chromatography-mass spectrometry to measure deuterium enrichment and calculate proliferation rates.
What was found
Total peripheral blood B cells divided at a mean rate of 1.9% (±1.0%) per day in young adults and 1.5% (±1.3%) per day in elderly adults. Naive peripheral blood B cells divided at 0.46% per day, whereas memory B cells divided at 2.66% per day.
Why it matters
This provides direct in vivo human evidence that circulating memory B cells have a substantially higher basal turnover rate than naive B cells, supporting the concept that B-cell memory is maintained by actively proliferating clones.
Limits
The abstract does not state the sample size (n) or participant demographics beyond general age categories. Measurements are limited to peripheral blood and do not assess tissue-resident B cells in lymphoid organs or bone marrow. Variance metrics (such as standard deviations or confidence intervals) for the naive and memory subset rates are omitted from the abstract.
Cited by
- contradicts The cells that make up the human immune system turn over and are replaced with new cells every 90 to 120 days.