Fig. 8

Melatonin promotes NK cell function by enhancing IL-2 secretion from CD4 + T cells rather than directly acting on melatonin receptors. (A) Splenic NK cells were isolated from aged mice (1 × 10^6), pre-treated with S26131 (MT1 antagonist, 10µM) or 4-P-PDOT (MT2 antagonist, 10µM) for 1 h, followed by treatment with 100µM melatonin for 24 h, NK cell CD107a expression was detected using flow cytometry. (B) The statistical graph of NK cell CD107a expression. (C) Splenic NK cells were isolated from aged mice (1 × 10^6), pre-treated with S26131 (MT1 antagonist, 10µM) or 4-P-PDOT (MT2 antagonist, 10µM) for 1 h, followed by treatment with 100µM melatonin for 24 h, NK cell IFN-γexpression was detected using flow cytometry. (D) The statistical graph of NK cell IFN-γ expression. (E) Flow cytometry was employed to assess the expression of IL-2 in CD4 + T cells from the spleens of aged mice treated with melatonin or control. (F) The statistical graph of IL-2 expression in CD4 + T cells. (G) We used a CD4 + T cell isolation kit to deplete CD4 + T cells from splenic PBMCs of aged mice, followed by treatment of the remaining PBMCs with 100 µM melatonin for 24 h, and assessed NK cell IFN-γ expression using flow cytometry. (H) The statistical graph of NK cell IFN-γ expression. The data is presented as means ± SD. n = 6. Unpaired two-tailed Student’s t-tests or one-way ANOVA. were conducted using Prism software. A p-value of less than 0.05 was considered statistically significant. *P < 0.05, **P < 0.01