Fig. 1

p16 expression increases in “aged” MCs. a. Representative histograms of p16 expression by PMCs derived from mice of the indicated ages. p16 expression was monitored in FcεRI⁺c-KIT⁺ cells. b. Pearson correlation of p16 expression (MFI) and age (r = 0.9635, p ≤ 0.0001). Each data point derived from flow cytometric analysis represents PMCs of a single mouse (total n = 10). Data was generated in two independent experiments containing mice of varying ages. c. Representative images of human skin sections of a young (20-year-old female) and elderly (72-year-old female) human individuals stained for the MC marker tryptase (green), for p16 (magenta) and with DAPI (blue). The dashed white line marks the border between dermis and epidermis. Scale bar = 20 μm. Insets are enlargements of the boxed areas. White arrowheads point to p16-positive MCs. d. Quantification of the incidence of p16 expressing skin MCs (i.e. p16⁺tryptase⁺ cells) of the total MC population (i.e. tryptase⁺ cells). Population per age group is displayed. Data is presented as means ± SEM. Statistical significance was determined by Welch’s t-test. n = 8 young and n = 9 elderly human individuals. Total number of analysed cells n = 405 young and n = 313 elderly