IL-15 produced by LPS-stimulated CD11c+ cells induce CD8+ Tregs.
(A and B) The expression levels of IL-15 mRNA in the total spleen (n = 3–4 per group) and various isolated cells (n = 4 per group) at indicated time after LPS administration were determined using quantitative RT-PCR. (C) Splenic CD11c+ or CD11c− cells were stimulated with LPS (100 ng/ml) for 24 h. IL-15 levels in the culture supernatants were detected using ELISA (n = 3 independent experiments). (D) Changes in the number of CD8+ Tregs prestimulation or poststimulation of IL-15 (100 ng/ml) with anti-CD3/CD28–coated beads (n = 4 independent experiments). (E and F) Naive CD8+CD44− T cells were stimulated with anti-CD3/CD28–coated beads in the presence or absence of IL-15 (100 ng/ml) for 5 d (n = 3 per group). The frequency of CD8+ Tregs was determined by FACS analysis. Representative histogram plots (E) and cumulative data graphical summary (F) are depicted. Data were presented as mean ± SD. Statically significant differences between the groups were determined using one-way ANOVA, followed by Tukey multiple comparisons test (A and B), and determined using a two-sided paired t test (D) or Student t test (C and F). *p < 0.05, **p < 0.01.