Fig. 4

f-LSCs negatively regulate the proliferation of CD4⁺, CD8⁺ lymphocytes and the induction of CD4⁺CD25⁺ regulatory T cells. a Representative dot plots of activated purified T cells collected by healthy volunteers and stained for the three activation markers CD28, programmed death (PD-1), and CD69 (left panel) are shown. Samples were run after 72 h of incubation with or without fibroblast-like limbal stem cells (f-LSCs). b A representative flow staining of activated CD4⁺ and CD8⁺ lymphocytes alone or after coculture is shown (left panel). In the right section the consequential CD4/CD8 ratio was calculated. c Gating strategy used to detect the CD4⁺CD25^highFoxp3⁺ fraction in T cells collected by healthy volunteers and stimulated with anti-CD3/CD28 for 3 days with or without f-LSCs. In all experiments unstimulated PBMCs were used as a negative control. Numbers in the corner of each quadrant correspond to the percentage of the corresponding cell population inside any dot plot. Also shown are the average results from five independent experiments. Data are presented as means ± SE in each histogram; *p < 0.05, **p < 0.02. NC normal control