Fig. 1

Mechanism of cell-to-cell contact between MSC and NK cells. IL-15-, IL-2-, IL-21-stimulated NK cells release inflammatory cytokines. These inflammatory cytokines affect the MSC and caused the release of PGE2 and kynurenine and other factors from the MSC. The MSC inhibits the function of NK cells by these factors. PGE2 prostaglandin E2, IL-15 interleukin-15, IL-2 interleukin-2, IL-21 interleukin-21, COX-2 cyclooxygenase-2, IDO indoleamine-2,3-dioxygenase, AA acid arachidonic, PG-H2 prostaglandin H2, IL-1β interleukin-1β, IFN-γ Interferon gamma, TNF-α Tumour Necrosis Factor alpha, EP2/3 Prostaglandin receptor, FOXO3A/CDKN1B quiescence-associated genes, IL-10 interleukin-10, HLA-G5 Human leukocyte antigen-G5, TGF-β Transforming growth factor beta, STAT4 signal transducer and activator of transcription, JAK Janus kinase, NK cell natural killer cell