Cell 178, 202–215.e14 & 178, 190–201.e11 (2019)

Passive transfer of maternal antibodies provides early immunological protection to neonates. In Cell, Jennewein et al. report the preferential transfer of human natural killer cell–activating antibodies from mothers to neonates. This property is due to digalactosylation of immunoglobulin G constant-fragment (Fc) domains, which enhance placental transfer via the neonatal Fc receptors FcRn and FcγRIIIA that are co-expressed on trophoblasts. Also in Cell, Martinez et al. report that mothers infected with human immunodeficiency virus (HIV) exhibit inefficient placental transfer of antibodies, which increases the susceptibility of HIV-exposed, uninfected neonates to post-partum infection. Curiously, maternal hypergammaglobulinemia is associated with poor placental transfer in HIV-infected mothers. Similarly, differences in Fc glycosylation affect the interactions of immunoglobulins with Fc receptors that mediate placental transfer. Those last findings suggest that maternal infection alters the glycosylation patterns during antibody production that can then affect the efficiency with which maternal passive antibody protection is provided to the offspring.