Marilen Benner

UTERINE LYMPHOCYTES GAIN EXPERIENCE DURING PREGNANCY 29 2 Figure 1. Lymphocyte composition of peripheral blood, menstrual blood, and term decidua. Mononuclear cells were isolated from peripheral blood (PBMC, n=17), menstrual blood (MMC, n=17), and decidua parietalis (DPMC, n=12). Percentages of lymphocytes (CD45+) based on side scatter (SS) and forward scatter (FS), T cells (CD56-CD3+; CD4+ and CD8+), NKT cells (CD3+CD56+), NK cells (CD3-CD56+; CD56+CD16+ and CD56+CD16-), and B cells (CD19+) were obtained by flow cytometric analysis. *p < 0.05, **p < 0.01, and ***p < 0.001 (lines indicate mean, non-parametric Kruskal-Wallis with Dunns post-hoc test). (46.9%±16.4% and 24.3%±10.6% respectively). MMC (43.9%±15.10%) contained a significant lower percentage of T cells, with an increased CD4 + /CD8 + ratio, as compared to DPMC (67.1%±10.66%). In addition, MMC contained significantly less NKT cells (1.2%±0.9% versus 2.5%±1.1%) compared to DPMC. No significant difference in percentages of B cells between MMC and DPMC could be observed. Also, important to note is that MMC and DPMC derived lymphocytes are from mucosal origin since more CD69 + and CD103 + , and less CD62L + T and NK cells can found compared to PBMC (Supplementary Figure S2). After showing that MMC and DPMC clearly differ in immune cell composition, we investigated T cells in more depth for differences between pre-pregnancy endometrium and decidua.