Granulocyte-macrophage colony-stimulating factor (GM-CSF) targets myeloid leukocytes in the uterus during the post-mating inflammatory response in mice.

Factors in seminal plasma elicit a surge of GM-CSF expression in uterine epithelial cells after mating in mice. This study investigates the nature of the endometrial cell populations targeted by epithelial GM-CSF. In quantitative RT-PCR studies, expression of the alpha-subunit of the GM-CSF receptor (GM-CSF-R) parallelled GM-CSF expression, being maximal during the 48 h period after mating and declining thereafter. Expression of mRNA encoding beta-common chain (AIC2B) also increased after mating and remained high until the time of embryo implantation on day 4 of pregnancy. Cells expressing GM-CSF receptors were identified in sections of uterus on the day after mating using 125I-GM-CSF, and were located predominantly in the endometrial stroma subjacent to the luminal epithelium, co-localising with abundant populations of myeloid leukocytes. Cells expressing GM-CSF receptor were identified as macrophages, granulocytes and putative dendritic cells by flow cytometric analysis using lineage and receptor subunit specific antibodies. Recombinant GM-CSF injected into the uterine lumen of ovariectomised mice was found to elicit a dose-dependant accumulation of macrophages and granulocytes in the endometrium, in a pattern of distribution comparable to that seen in uteri after natural mating. Together, these data indicate a role for epithelial cell-derived GM-CSF in mediating the recruitment and potentially in modifying the behaviour of uterine leukocytes during the post-mating inflammatory response in mice.