Functional Regulation Of Plasmacytoid Dendritic Cells By Mouse Splenic Stromal Microenvironment

PDCs are a unique subset of immunocytes involving innate and adaptive immune responses. The most obvious characteristic of pDCs is their rapid and robust secretion of typeⅠIFN when exposure to virus or other pathogens, subsequently promoting and regulating the function of other immunocytes. Here we use the mouse splenic stromal cells to mimic the microenvironment in vivo, and report the functional regulation of plasmacytoid dendritic cells (pDCs) by mouse splenic stromal microenvironment. Our data indicates that the splenic stromal microenvironment inhibits the typeⅠinterferon, IL-12, TNF-αsecretion and the antigen-presentation of VSV-activated pDCs. The splenic stromal microenvironment also inhibits the secretion of IFN-γfrom NK cells by VSV-activated pDCs. Furthermore, we found that TGF-βparticipates in regulating VSV-activated pDC to secret IFN-αin splenic stromal microenvironment. On the other side, resting pDCs premodified by splenic stromal microenvironment can be still activated to secrete large amount of typeⅠinterferon, IL-12 and TNF-αby VSV, suggesting that pDCs in stromal microenvironments are still functional cells in anti-virus immunity. In conclusion, with respect to pDCs, stromal microenvironment not only keeps immune defense but also plays a critical role in maintain the immunological homeostasis.