CD27(+) (memory) B cell decrease and apoptosis-resistant CD27(-) (naive) B cell increase in aged humans: implications...

Area of Science:

• Immunology
• Gerontology
• Cell Biology

Background:

• Humoral immunity undergoes significant changes with aging.
• B cell subsets, including naive (CD27-) and memory (CD27+) B cells, play crucial roles in immune responses.
• Understanding age-related B cell alterations is vital for addressing immune senescence.

Purpose of the Study:

• To investigate age-related quantitative and qualitative changes in peripheral B cell subsets.
• To analyze the expression of activation, proliferation, and apoptotic markers on B cells in aged versus young individuals.
• To evaluate the susceptibility of B cells to apoptosis in different age groups.

Main Methods:

• Flow cytometry was used to analyze peripheral B cell subsets (CD27(-) and CD27(+)) in 54 aged and 30 young individuals.
• Expression of CD38, Ki-67, CD95, and bcl-2 was assessed as markers for activation, proliferation, and apoptosis.
• Apoptosis susceptibility was evaluated using cell size and annexin-V binding assays.

Main Results:

• Aged individuals exhibited a lower percentage of CD27(+) memory B cells and a higher percentage of CD27(-) naive B cells compared to young individuals.
• The absolute number of CD27(+) B cells was reduced in aged individuals.
• Aged CD27(+) B cells showed reduced apoptosis susceptibility but higher CD95 expression, while aged CD27(-) B cells had higher CD38 and bcl-2 expression and decreased apoptosis susceptibility.

Conclusions:

• Human aging significantly alters the balance of naive and memory B cell populations.
• Age-related changes in B cell surface phenotypes and apoptosis regulation impact peripheral B cell homeostasis.
• These findings highlight quantitative and qualitative modifications in the B cell developmental system due to aging.