Natural Killer Cell Subpopulations and Cytotoxicity for Infertile Patients Undergoing In Vitro Fertilization

PROBLEM: We evaluated the participation of the lymphocyte subpopulations in the endometrium and peripheral blood on in vitro fertilization and embryo transfer (IVF‐ET) outcomes. METHOD OF STUDY: Peripheral blood samples were analyzed for the expression of CD3, CD4, CD8, CD16, and CD56, using a FACScan, and for natural killer (NK) cell cytotoxicity, using a 51 Cr assay. Endometrial samples obtained at a previous phase of the IVF cycle were analyzed for the expression of CD 16 and CD56, using a FACScan. RESULTS: The percentages of CD56 + cells and CD16 + CD56 + cells in the peripheral blood on the day of ET were significantly higher in the failed group than in the implanted group. In the endometrial tissue, the increase of the percentage of CD16 + CD56 dim cells and the decrease of the percentage of CD16 — CD56 bright cells in the aborted group were significant when compared with the those of the delivered group. CONCLUSIONS: The increase of cytotoxic NK cells in the peripheral blood and the endometrium may affect the therapeutic results of IVF‐ET. It was suggested that modifications of NK cytotoxicity or of NK subpopulations might contribute to the improvements of IVF outcomes.