WIKIMEDIA, SEWERYN OLKOWICZImmunoglobulin G (IgG) antibodies in breast milk prevent immune responses against the essential microbes that colonize the newborn mouse gut, according to researchers at the University of California (UC), Berkeley, and their colleagues. The team’s findings, published in Cell today (May 3), are somewhat surprising to immunologists who previously considered IgG a purely pathogen-fighting molecule.
“They found . . . that IgG acquired from the mother is important for regulating immune responses in the pup,” said immunologist Noah Palm of Yale University who was not involved in the study. “IgG was thought to be mostly involved in protecting against [pathogenic] infection,” he added, “but, in this case, it is actually shaping the response to the commensal microbiota.”
The benevolent bacteria of a mammal’s gut assist with digestion and immune function, among other things, so establishing colonies of these bugs after birth is essential for intestinal and general health. It is also important, however, that the newborn’s immune system is prepared for the influx of new bacteria and knows how to differentiate friendly bugs from harmful ones.
“We know that neonates ...
