Conclusion
These data suggest that DSCs promote the differentiation of CD56bright CD16- NK with high levels of inhibitory receptors, immunotolerant, and angiogenic cytokines by secreting IL-24 during decidualization in early pregnancy.
Results
The concentration of IL-24 in culture supernatant of DSCs was significantly higher than that of ESCs. Both eNK (endometrial NK cells) and dNK highly expressed IL-24 receptors (IL-20R1 and IL-22R1), especially on CD56dim eNK. However, there were extremely low levels of IL-20R1 and IL-22R1 on pNK. Recombinant human IL-24 or DSCs-secreted IL-24 downregulated the levels of CD16, Granzyme B, perforin, and interferon (IFN)-γ and upregulated the levels of inhibitory receptors killer-cell immunoglobulin-like receptor (KIR)2DL1 and KIR3DL1, or immunotolerant or angiogenic cytokines (eg, transforming growth factor (TGF)-β, IL-10, and IL-8), and elevated the percentage of CD56bright CD16- dNK in vitro.