Marilen Benner

IMMUNE PROFILES IDENTIFY RECURRENT PREGNANCY LOSS 115 5 NK bright CD27+ B cells NK dim %CD56HiCD16- of C56+ % CD16+CD56+ of C56+ % CD27+ of CD19+ PB MB PB MB PB MB ns (0.62) 0 25 50 75 100 * 0 25 50 75 100 CMV seropositivity negative positive not available Ctrl RPL Cohort A C B * 0 25 50 75 100 * 0 25 50 75 100 ns (0.082) 0 25 50 75 100 ns (0.28) 0 25 50 75 100 Figure 2. Univariate analysis of immune profiling shows uterine-specific deviations in RM patients. (A+B) NK cell profiles of peripheral blood (PB) and menstrual blood derived cells (MB). (C) Cytomegalovirus (CMV) seropositivity of CD27+ B cells. Additional results of univariate analysis are depicted in Supplementary Figure S3. Data were compared by Mann-Whitney/Wilcoxon tests (non-parametric), * p < 0.05, ns= non-significant. Ctrl, control; RPL, recurrent pregnancy loss. DISCUSSION Adaptations of the maternal immune system during pregnancy occur not only systemically, but also locally, where immune cells and soluble factors contribute to the contact of trophoblast cells and the maternal mucosa. Subtle changes in immunological profiles of both compartments may contribute to the etiology of recurrent pregnancy loss. To create a better understanding of dysregulated immunity in RPL, we assessed in how far the joint assessment of leucocyte subsets might reveal differences in PB or MB of affected women. By using an ensemble machine learning strategy and recursive feature selection, we were able to identify 4 cell subsets of PB and 6 cell subsets and age for MB, which, when combined, robustly allowed for cohort classification for either PB or MB. Based on general definitions describing the discriminative power of a diagnostic test, both PB and MB had “excellent” distinctive value (34, 35). Thus, RPL is associated with immune adaptations that can be traced back systemically and in the uterus. Classic univariate approaches often do not suffice when studying immunological data (14). Large overlap between frequencies in RPL and control cohort measured in PB and MB hampers the individual discriminative value of a cell type. Furthermore, differences in cell types of low