DEVELOPMENT AND VALIDATION OF AN ASSAY FOR MEASURING PREIMPLANTATION FACTOR (PIF) OF EMBRYONAL ORIGIN

PROBLEM: Tests to determine presence of embryos prior to implantation are needed. METHODS: Sera from women after embryo transfer were tested for preimplantation factor (PIF) using the lymphocyte/platelet bindin g assay. Autorosettes were counted using blood type O+ donor lymphocyt es and platelets incubated with blinded serum in the presence of antiC D2 antibody and rabbit complement. Human chorion gonadotropin (hCG) co ncentrations were determined 7 days later and compared with results of the lymphocyte/platelet assay. Implantation was confirmed by ultrason ographic evidence of presence of an intrauterine gestational sac. The roles of platelet activating factor (PAF) and chaperonin 10 in the obs erved phenomena were studied experimentally. RESULTS: Significantly mo re lymphocyte/platelet rosette formations were observed when sera from women who successfully implanted were compared to sera from women who failed to implant. Neither PAF nor chaparonin added to the tested ser a controls influenced the percentage of lymphocyte/platelets rosettes. CONCLUSIONS: PIF is a likely candidate to be the next frontier of dia gnosing the presence of viable preimplantation embryos in vivo.