Effects Of Adoptive CD49b~+CD25~+NK Cell Transfer On The Fertility Of NOD Mice

Objectives:To investigate the role that CD25+natural killer (NK) cells may play in the establishment of pregnancy, the effect of adoptive CD49b+CD25+NK cell transfer on pregnancy outcome in subfertile non-obese diabetic (NOD) mice was investigated.Materials and Methods:Allogeneic NOD (H-2g) X C57BL/6 (H-2Kb) mating combination was established, and Balb/c (H-2d) X C57BL/6 (H-2Kb) was used as the normal control. A total of 50 female NOD mice and 55 female Balb/c mice were observed for 16 weeks to evaluate the percentage of infertility. Splenic CD49b+CD25+NK cells were purified using magnetic affinity cell sorting (MACS). The purity of these cells and the Foxp3+percentage within these cells were detected using flow cytometry. The purified CD49b+CD25+NK cells were transferred to subfertile NOD mice. The subfertile NOD mice were divided into three groups receiving CD25+NK cells (group 1), CD25-cells (group 2) or RPMI 1640 medium only (group 3). The spleen and uterine NK cell phenotype analysis, including the expression pattern of CD25, Foxp3, TNF-a, IL-4, TGF-βand IL-10 molecules in the NK cells, was performed by flow cytometry before and after the transfer.Results:The proportion of subfertile NOD female mice that failed to become pregnant when co-caged with C57BL/6 males for 16 weeks was significantly higher in female NOD mice than in normal female Balb/c controls (53.1%versus 15.1%; P< 0.01). Group 1 had significantly more pregnancies than those receiving CD25- NK cells (77.8%versus 11.1%; P< 0.01) and controls injected with RPMI 1640 medium (0.0%; P< 0.01). The receiving CD25+NK cells group had a significantly higher percentage of CD25, Foxp3, TGF-P and IL-10. The low resorption rate group had a significantly higher percentage of Foxp3+NK cells than the high resorption rate group (19.2 versus 5.5%; P＜0.05). Improved fertility was concomitant with an increase in uterine CD49b+NK cells expressing Foxp3. Foxp3 expression was confirmed in the CD49b+CD25+NK cells before the transfer.Conclusions:The maintenance of pregnancy and the embryo resorption rates of NOD mice related to the expression of Foxp3 on uNK cell. These results indicate that subfertility in NOD mice may be partially attributed to the insufficiency of CD25+and Foxp3+NK cells recruited into the pregnant uterus. Adoptive transfer of splenic CD49b+CD25+NK cells can decrease the percentage of infertility in NOD×C57BL/6 mice.