Decreased Peripheral Blood CD4(superscript +)CD25(superscript bright) T Cells in Women with Repeated Implantation Failures after in Vitro Fertilization and Embryo Transfer

Objective: To investigate peripheral blood CD4(superscript +)CD25(superscript bright) T cells in non-pregnant women with repeated implantation failures (RIFs) after two or more in vitro fertilization and embryo transfer (IVF-ET) cycles, those with recurrent spontaneous abortion (RSA) and those with normal fertility (controls). Methods: Proportions of circulating CD4(superscript +)CD25(superscript bright) T cells within CD4(superscript +) T cells and absolute numbers of CD4(superscript +)CD25(superscript bright) T cells in 25 women with RIF, 18 women with RSA and 21 controls were determined by flow cytometric analysis. Results: Significantly lower proportions of peripheral blood CD4(superscript +)CD25(superscript bright) T cells within CD4(superscript +) T cells were observed in women with RIF (median=3.95%, interquartile [IQ] range 2.52-5.70%) than those in controls (median=5.39%, IQ range 4.36-6.74%, p＜0.0083). Significantly lower absolute numbers of peripheral blood CD4(superscript +)CD25(superscript bright) T cells were observed in women with RIF (median=24.5 cells/μL, IQ range 12.9-32.0 cells/μL) than those in controls (median=36.6 cells/μL, IQ range 23.8-44.2 cells/μL, p＜0.0083). After excluding women with RIF with a history of RSA, the proportions and the absolute numbers of peripheral blood CD4(superscript +)CD25(superscript bright) T cells were still significantly lower than those in controls (p＜0.0167 for both). Conclusion: Decreased peripheral blood CD4(superscript +)CD25(superscript bright) T cells in women with RIF may be involved in the pathogenesis of implantation failures.