Phenotypic characterization of macrophages in the endometrium of the pregnant cow.

PROBLEM Macrophages are recruited in large number to the interplacentomal endometrium of the cow during pregnancy. We evaluated whether endometrial macrophages also accumulate in placentomal regions of endometrium during pregnancy and whether endometrial macrophages are regionally differentiated. METHOD OF STUDY Interplacentomal endometrium and placentomes were subjected to dual-color immunofluorescence using CD68 as a pan-macrophage marker. RESULTS CD68(+) cells were abundant in stroma of the interplacentomal endometrium and caruncular septa of the placentomes. CD68(+) cells were not present in fetal villi of the placentomes or in the interplacentomal chorion. Regardless of location, the majority of CD68(+) cells also expressed CD14. In interplacentomal endometrium, CD68(+)CD11b(+) cells were present in deeper areas of the stroma but not in shallow endometrial stroma. In caruncular septa of the placentome, CD68(+) cells were negative for CD11b. CD68(+) cells in the interplacentomal endometrium were negative for MHC class II while most CD68(+) cells in caruncular septa were positive for MHC class II. CONCLUSION CD68(+)CD14(+) macrophages present in the stroma of the interplacentomal endometrium and caruncular septa of the placentome are regionally differentiated with regard to expression of CD11b and MHC class II.