Uterine natural killer (uNK) cells are enriched in the post‐ovulatory uterus and during pregnancy. Whether these cells arise from blood pre‐cursors or from stem cells in the uterus is undefined. To support a hypothesis that precursors of uNK cells are recruited from blood, adhesive function of blood CD56+ subsets were assessed during one cycle and during pregnancy.
Method of study
Fifteen women of proven fertility provided serial blood samples during one menstrual cycle and thirty women with a history of implantation failure or recurrent spontaneous abortion provided serial samples during infertility treatment.
CD56bright cells, but not CD56dim cells or NKT cells, increased in ligand‐binding capacity during ovulation in fertile cycles only and during the first 2 weeks from date of missed menses.
Enhanced adhesive function at ovulation in CD56bright cells in fertile cycles and during early gestation supports a hypothesis of recruitment of pre‐uNK cells from the blood CD56bright subset.