Geriatrician George Kuchel, immunologist Jacques Banchereau and their team have been working to identify the specific regions of DNA that lose function with aging. The sheer volume and variety of data even required the invention of new methods of analysis. The study involved 75 healthy people aged 22-40 years and 26 healthy people aged 65 years or older. A blood sample was taken from each subject. The research team isolated immune cells (peripheral blood mononuclear lymphocytes, as well as monocytes, B-lymphocytes and T-lymphocytes) from the blood to assess age-related changes in the activity of genes responsible for their synthesis. Combined analyses of chromatin accessibility, which carries information about the immune cells studied, and the transcriptome (the result of reading from a DNA strand) revealed activity in the young adult group and a decrease with age. The IL7R interleukin genes and IL-7 signalling pathway genes were also found to be repressed, which could be used as biomarkers of ageing in the future. These genes are necessary for the work of CD8+ T-lymphocytes, which store information about previous infections and form secondary immunity. Thus, human aging is associated with changes occurring in chromosomes. The findings provide further insight into the mechanisms of age-related immunodeficiency and could be used to assess the response of the elderly organism to vaccination – the authors of the article are currently studying the pneumococcal vaccine in this light.