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The aim of the study was to investigate whether normal aging leads to blood cells being produced from fewer cell clones. This was examined by comparing which X chromosome the cells were using between different age groups and between neutrophils and T cells.
In other words, they studied human hematopoiesis acros s age by analyzing purified blood cell lineages from the subjects.
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## Study
- 197 hematologically normal females
| | Sample size | Age | Median |
| ----------- | ----------- | ----- | ------ |
| Newborn | 23 | 0 | 0 |
| Young adult | 94 | 17-50 | 30 |
| Eldery | 80 | 75-96 | 81 |
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### Methods
- Peripheral blood samples were collected
- Neutrophils and T cells were isolated using cell separation techniques _(centrifugation followed by lineage-specific purification)_
- X-chromosome inactivation was analyzed using the HUMARA PCR assay _(PCR-based measurement of which X chromosome is active)_
- T cells were analyzed by PCR to check for clonal expansion _(T-cell receptor γ gene rearrangement analysis)_