Identification of the Predominant Proteins in Uterine Fluids of Unilaterally Pregnant Ewes that Inhibit Lymphocyte Proliferation1

Abstract

Uterine fluid from unilaterally pregnant ewes contains activity inhibitory to lymphocyte proliferation. The molecules responsible for this activity may thereby regulate uterine immune responses during pregnancy. The purpose of the experiment described here was to identify the major protein in uterine fluid responsible for this activity. When uterine fluid was fractionated by a combination of cation exchange chromatography, gel filtration, and lectin affinity chromatography, the majority of the lymphocyte activity co-migrated with a pair of proteins previously identified as related, serpin-like glycoproteins. Together, this pair of proteins, called the uterine milk proteins (UTM-proteins), are the predominant endometrial secretory protein produced under the influence of progesterone. Preparations of uterine protein highly enriched for the UTM-proteins inhibited lymphocyte proliferation induced by phytohemagglutinin, concanavalin A, and mixed lymphocyte reactions but did not inhibit proliferation induced by pokeweed mitogen. In some experiments, UTM-proteins also reduced viability of cultured lymphocytes. Another previously described lymphocyte-inhibitory factor, megasuppressin, was also observed. Megasuppressin, which eluted at an apparent molecular weight of greater than 4 x 10(6) even after treatment with urea, guanidine-HCl, and beta-mercaptoethanol, was a more potent inhibitor of lymphocyte proliferation than UTM-proteins. Megasuppressin is not very abundant, however, and probably is responsible for only a small fraction of the lymphocyte inhibitory activity in uterine fluid. The majority of lymphocyte-inhibitory activity is caused by the UTM-proteins or by a molecule that co-purifies in trace amounts with UTM-proteins.

Local versus systemic control of numbers of endometrial T cells during pregnancy in sheep

“…Chief among these immunosuppressive molecules is OvUS, which can inhibit a variety of T‐cell‐ and NK‐cell‐mediated phenomena 18 . In addition, PGE 2 and TGF‐β, both of which can inhibit lymphocyte proliferation in sheep, 29,30 are produced by the endometrium of pregnant ewes 19,21 . The failure of a decrease in CD45R + cells in the luminal epithelium, despite the fact that progesterone treatment reduced numbers of CD45R + cells in both glandular and luminal epithelium, 16 probably reflects the increase in γδ T cells in the lumen, since these cells are CD45R + 11 .…”

Pepsin-inhibitory activity of the uterine serpins

“…These ovine uterine serpins (now called ovUS) have been reported to be immunosuppressive (15,16) and may prolong the ability of skin grafts to survive within the uterus (17). They have not been shown to possess any antiproteinase activity (14).…”

Changes in expression of cell‐cycle‐related genes in PC‐3 prostate cancer cells caused by ovine uterine serpin

“…Ovine US did not cause cytotoxic or apoptotic effects on lymphocytes or PC-3 cells [Skopets and Hansen, 1993;Tekin et al, 2005a;Padua and Hansen, 2008]. It was recently determined that OvUS blocks cell-cycle progression in mitogenstimulated lymphocytes and increases the number of cells at the G 0 /G 1 stage at 96 h after addition of protein [Padua and Hansen, 2008].…”