Changes in mononuclear immune cells during bovine pregnancy

This study aimed to determine the differences in gene expression between mononuclear cells derived from peripheral blood and endometrium during pregnancy in cattle and to determine the proportion of mononuclear cells in the endometrium of pregnant and diestrous cows. Endometrial tissue and peripheral blood were collected from Day 34±2 pregnant cows, and mononuclear cell populations were quantified and sorted (n=5). The relative mRNA levels of inflammatory mediators was assessed by quantitative real time polymerase chain reaction. During pregnancy, the proportion of CD8+, CD4+, CD4+CD25− and CD4+CD25dim cells among mononuclear cells was greater in blood than endometrium, and cells positive for CD14 and CD68 expressed greater mRNA amounts of interleukin (IL) 6, CXCL8 and IL10 in endometrium compared with blood. Cells positive for γ/δ-T cell receptor expressed greater amounts of IL1A transcript in the endometrium than in blood of diestrous cows, CD4+CD25bright cells expressed more CTLA4 mRNA in the endometrium compared with blood of diestrous cows, and endometrial natural killer cells expressed greater CXCL8 mRNA compared with blood of pregnant and diestrous cows. The percentages of CD21+, NCR1+, CD8+, FoxP3+, CD3+ and CD68+ cells were greater in the endometrium of Day 35 pregnant cows compared with diestrous cows.