Study Design
Samples of amniotic fluid (AF) collected at >37 weeks of gestation (North of Scotland Research Ethics Committee: 06/S0801/77) and breast milk (BM) collected at 2 (2W) and 6 weeks (6W) postpartum (Wales Research Ethics Committee: 2004/024) archived prior to the COVID-19 pandemic were available. All samples were rendered cell free by centrifugation and breast milk defatted prior to arhciving. ELISAs (DuoSet, R&D Systems) were performed to determine the concentration of sACE2 (catalogue number: DY933), sCD26 (DY1180), sCD147 (DY972) and sNRP-1 (DY3870) in AF and 2W and 6W BM (Figure 1A). Statistics were performed using a one-way ANOVA; a p value of < 0.05 was deemed significant. Immunoblotting analysis (ACE2 (15983), CD26 (67138), Cell Signalling Technologies; CD147 (AF972), Bio-Techne; NRP-1 (ab81321), Abcam) was used to confirm findings from the ELISAs and reveal different isoforms (Figure 1B).