Evidence that FcRn mediates the transplacental passage of maternal IgE in the form of IgG anti-IgE/IgE immune complexes.

"Conflict of interest The authors declare no conflict of interest."

"The authors thank Lynn Puddington and Michelle Cloutier for their guidance and mentorship, Justin Radolf for his critical evaluation of the manuscript, and Kristi Baker for her advice in performing the MDCK transcytosis assay. We thank Jennifer Moller and Amanda Augeri for their assistance in recruiting subjects and collecting biologic specimens. We thank Derry Roopenian for suggesting the FcRn blocking experiments using DVN24 and providing the antibody, and Robert Hamilton for suggesting the subclass‐specific IC assays and providing the necessary antibodies. We also thank members of the Obstetrical Staff at Hartford Hospital for their support of this project. This work was supported by the National Institutes of Health (NIH): K08AI071918 (to Adam P. Matson), NIH DK53056 (to Richard S. Blumberg), and by funds made available through a Connecticut Children's Medical Center Young Investigator Award (also to Adam P. Matson)."