The role of collagen in the function of dNK cell. The interaction of collagen with integrin β1 may promote the adhesion of dNK cell, and then contribute to the residence of NK cell in decidua. And collagen binds to the LAIR-1 which is expressed on dNK cell, triggers the SHP-1 binding to JAK1 and JAK2 in dNK cell. Resulting in the phosphorylation of STAT1 and STAT4 reduction, and then the production of IFN-γ and TNF-α is decreased. In addition, collagen could reduce the cytotoxicity receptor NKp30 expression, and increase the inhibitory receptor KIR2DL1 expression on dNK cell. The production of perforin is also decreased by collagen. These results mentioned above leads to decreased cytotoxicity and activity of dNK cell. Therefore, collagen plays a key role in the function of dNK cell, and then contributes to the immune tolerance at the maternal fetal interface.