medical-notes/content/Vetenskaplig artikel/Methods & Main Results.md

The aim of the study was to investigate whether normal aging lea. ds 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 across age by analyzing purified blood cell lineages from the subjects.

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Study

• 1 97 hematologically normal females
  • 23 newborn
  • 94 young adult (median 30)
  • 80 eldery (over 75)
• purified neutrofils
• purified T-cells

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Methods

1. Peripheral blood samples were collected
2. Neutrophils and T cells were isolated using cell separation techniques (centrifugation followed by lineage-specific purification)
3. X-chromosome inactivation was analyzed using the HUMARA PCR assay (PCR-based measurement of which X chromosome is active)
4. T cells were analyzed by PCR to check for clonal expansion (T-cell receptor γ gene rearrangement analysis)

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Results

1. X chromosome usage is similar in newborns and young adults.
2. Neutrophils from elderly female individuals show strongly uneven X chromosome usage.
3. T-cells show much less uneven X chromosome usage and no dominant clonal expansion

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Cord blood neutrophils

!image-183.png

• Graph shows the distribution of X chromosome usage in 23 newborn
• X-axis: % of cells using the less common X chromosome.
• Y-axis: number of individuals in each group. Conclusion: Newborns mostly show balanced use of the two X chromosomes

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> 75 years neutrophils

!image-184.png

• This graph shows the purified neutrofils from 80 elderly (y >= 75) females
• X and Y axis is the same as in previous graph Conclusion: Elderly neutrophils frequently show strongly uneven X chromosome usage.