[Significance of early pregnancy factor (EPF) on reproductive immunology]

We studied the significance of Early Pregnancy Factor (EPF), which appeared very soon after fertilization, on reproductive immunology. The results were as follows: EPF inhibited dose-dependently mixed lymphocyte reaction (MLR). EPF suppressed recognition phase of MLR. And EPF induced nonadherent, Thy 1.2+, Lyt 1-, Lyt 2+ regulator cells as suppressor T cells. Immunosuppressive effect of EPF was not restricted by major histocompatibility complex (MHC). Administration of anti EPF antibody in period before implantation of mice decreased the number of implantations and neonates. It suggested that EPF was important in this stage of reproduction.