Embryo implantation associated with increase in T-cell suppressor factor in the uterus and spleen of mice

The concentrations of T-cell suppressor factor (TsF) were examined by competitive binding assays in the uterus, spleen, and regional lymph nodes draining the uterus in Day-5 pregnant mice or in ovariectomized mice given hormone treatments to induce conditions of delayed implantation or implantation. The amounts of immunoreactive TsF on Day 5 of pregnancy were 2.055 +/- 0.302, 0.803 +/- 0.088, 0.426 +/- 0.136 ng TsF/mg extractable protein for the regional lymph nodes, spleen and uterus, respectively, during Day 5 of pregnancy. When implantation was prevented by ovariectomy on Day 4 followed by treatment with only progesterone, amounts of TsF (as a % of Day 5 value) were decreased to 57% in the uterus and increased to 141% in the spleen and 180% in the regional lymph nodes. When implantation was then initiated with the addition of oestradiol-17 beta to the progesterone treatment, amounts of TsF were increased to 206% in the uterus, 318% in the spleen, and remained unchanged at 180% in the regional lymph nodes. These experiments suggest that the amounts of TsF in the uterus and spleen are dependent upon the implantation process, whereas amounts of TsF in the regional lymph nodes are independent of this event.