Abstract： Objective To explore the expression and significance of chemokine CXC reeeptor (CXCR)3 and CXCR4 and their ligands(CXCL)at the early pregnancy decidua and villi.Methods Decidual mononuclear cells were isolated from the normal decidua of 5-8 weeks pregnant women by lymphocyte separation medium in vitro.CD56+natural killer(NK)cells were purified by dynabeads cell sorter kiL Purity and phenotype of CD56+decidua NK cells were analyzed by fluorescence-activated eell sorter (FACS).Gene expression of CXCR3 and CXCR4 in decidua NK cells and CXCL9,CXCL10 and CXCL12 in early pregnancy decidua and villi was assessed bv RT.PCIZ Protein expression of CXCL9,CXCL10 in normal endometrium and early pregnancy decidua was characterized and quantified by streptavidin-biotin pemxidase chain reaction(SP)immunohistochemistry and computered image analysis system.Correlations between the gray degree of CXCL9 and CXCL10 and the number of CD56+NK cells in upper tissue were analyzed by Spearman's correlation ceefficient rank tesL Results The phenotype of 98.7%decidua NK cells was CD56bright.The genes of CXCR3 and CXCR4 were expressed in decidua NK cells and that of CXCL9 and CXCL1O were expressed in early pregnancy decidua and CXCLI2 in early pregnancy villi.CXCL9 and CXCL10 were expressed in the cytoplasm of surface epithelia,glandular epithelia and stromal cells of early pregnancy deeidua and were not expressed in villi by immunohistochemistry.The gray degree of CXCL9 and CXCL10 in the secretory phase endometrium(56±43,59±47)was stronger than that in the proliferative phase(16±18,8±14,P<0.05)and reached the highest(143±35,158±29,P<0.05)in the early pregnancy decidua.The number of cD+56 NK cell in the secretory phase endometrium(60±20)was more than that in the proliferative phase endometrium(23±4,P<0.05)and was the most in the early pregnancy decidua(114±15,P<0.05).The gray degree of CXCL9 in upper tissue had a positive correlation with the number of CD+56 cells(r=0.88,P<0.05)and that of CXCL10 had a similar pattern to CXCL9(r=0.86,P<0.05).Condusion The interactions between CXCL9,CXCL10 and CXCL12 expressed in decidua and villi and CXCR3,CXCR4 expressed in CD+56 decidua NK cells may influence the CD+56 NK cell recruitment at the maternal-fetal interface.