Multi-factorial regulatory networks of placental antibody transfer by Fc receptors and maternal IgG Fc characteristics are modulated by clinical covariate profiles.

Maternal immunoglobulin G (IgG) transferred across the placenta is crucial for newborn immunity. IgG transfer efficiency modulated by Fc characteristics including subclass and glycosylation gives rise to diverse transfer profiles across the population, yet the molecular mechanisms driving this variation are incompletely understood. To disentangle multimodal molecular relationships driving population heterogeneity in maternal-fetal antibody transfer, we characterized placental and serological antibody features in matched human tissues from two geographically distinct cohorts. Unsupervised clustering of maternal clinical covariates in both cohorts revealed a distinct patient profile with reduced plasma C-reactive protein and pregravid BMI and enhanced transfer efficiency of IgG subclasses. Quantification of IgG Fc glycan structures in matched maternal and cord plasma by liquid chromatography-mass spectrometry revealed subclass-specific IgG glycosylation patterns which impacted placental transfer efficiency and correlated with these key clinical features. We profiled expression and colocalization of key Fc γ Receptors (FcγRs) by multiplex immunohistochemistry, revealing cell type-specific expression patterns. Variable FcγR expression across gestation was consistent in both cohorts, implicating FcγRs as key drivers of temporal antibody transfer dynamics. While FcγRs were not strongly variable across the clinical profiles, partial correlation analysis of matched samples controlling for gestational age and demographic covariates revealed correlations between FcγR expression frequencies and glycan- and subclass-specific transfer efficiency. These data systematically define multi-factorial regulatory networks of antibody transfer by placental Fc receptors and maternal IgG Fc characteristics, which are further modulated by clinical covariates. This study provides a basis for the rational design of prenatal vaccination strategies, administration schedules, and potential lifestyle interventions to improve maternal-fetal immunity.