Immunosuppressive activity and alpha interferon concentrations in human embryo culture media as an index of potential for successful implantation.

OBJECTIVE: To evaluate potential correlations between establishment of pregnancy and immunosuppressive activity secreted by the preimplantation embryo. DESIGN: To evaluate immunosuppressive activity, supernatants from preimplantation embryos were assessed for their ability to inhibit lymphocyte proliferation. Additionally, alpha interferon concentrations were also measured in these supernatants. We compared these parameters from embryo culture supernatants of women who did and did not achieve pregnancy after in vitro fertilization (IVF). Immunosuppression was assessed using a lymphocyte proliferation assay with concanavalin A (Con A) and phytohemagglutinin (PHA) as mitogens. SETTING: In vitro fertilization program at the University of Utah Medical Center. PARTICIPANTS: Couples less than 40 years of age, with normal semen quality and bilateral tubal obstruction. RESULTS: Immunosuppression calculated using the stimulation index (mean +/- SEM) in pregnant and nonpregnant women, respectively, were: Con A: 43.9 +/- 3.9 versus 19.1 +/- 10.1, P less than 0.04. PHA: 23.6 +/- 5.6 versus 12.5 +/- 12.8, P less than 0.02. Alpha interferon levels (mean +/- SD) in pregnant and nonpregnant women were not significantly different: 23.98 +/- 9.6 U/mL versus 24.79 +/- 2.5 U/mL. CONCLUSIONS: We conclude that pre-embryos with the capacity for successful implantation secrete greater amounts of immunosuppressive factors than those destined not to implant, as measured by Con A and PHA lymphocyte proliferation assays. Refinement of assay techniques and identification of the substances involved could have significant impact on IVF programs.