Gonadotropin Releasing Hormone (GnRH) Agonist Induces Down‐Regulation of the CD3⁺CD25⁺ Lymphocyte Subpopulation in Peripheral Blood

PROBLEM: To test whether GnRH agonist could alter in vivo human immune cells and whether the alteration is related to the success of pregnancy in an in vitro fertilization‐embryo transfer (IVF‐ET) program. METHODS: Thirty‐six infertile patients were enrolled under the long protocol of GnRH agonist (buserelin acetate) and superovulation with gonadotropin from our IVF‐ET program. Peripheral B cells, NK cells, CD4⁺ and CD8⁺ T cells, and the expression of CD69, CD25, HLA‐DR, and CD71 antigens on the T cells were serially examined by dual‐color flow cytometry. RESULTS: B cells, NK cells, CD8⁺ T cells, and CD71⁺ T lymphocyte subpopulations were not changed throughout the whole course of treatment. CD4⁺ T cell and CD25⁺ T cell sub‐populations were significantly down‐regulated when the GnRH agonist was used for approximately 2 wk. CD3⁺CD69⁺, CD3⁺CD25⁺, and CD3⁺DR⁺ lymphocyte subpopulations were increased at 7 days (during implantation) and at 14 days after embryo transfer in pregnant patients, but not in patients who failed to get pregnant. CONCLUSIONS: The GnRH agonist had a transiently immunosuppressive effect on CD4⁺ and CD25⁺ T cells, but CD69⁺, CD25⁺, and HLA‐DR⁺ T cells were activated during and after successful implantation. 1995 Munksgaard