Social stress in pregnant squirrel monkeys (Saimiri boliviensis peruviensis) differentially affects placental transfer of maternal antibody to male and female infants

The capacity of prenatal stress to disrupt the placental transfer of matern al antibody was evaluated in neonatal squirrel monkeys (Saimiri boliviensis peruviensis) gestated under different pregnancy conditions. Normal squirre l monkey offspring (n = 63) were compared with infants generated from pregn ancies that involved either a single or 3 periods of disturbance (ns = 21 a nd 29, respectively). At parturition, levels of antibody (IgG) were determi ned in mothers and neonates. Only the chronic disturbance condition signifi cantly altered antibody levels in the mothers, resulting in lower IgG. Anti body transfer to the fetus was also affected only by chronic disturbance. I n this case the effect was bidirectional, influenced by the sex of the infa nt Males were born with lower levels, whereas female infants actually had h igher-than-normal IgG, despite lower titers in their mothers. Because virtu ally all Ige is derived from the prenatal transfer of maternal antibody, it indicates that the sex of the fetus differentially affected this placental process. The IgG receptor may have been Up-regulated selectively on the pl acentas of female fetuses, compensating for reduced antibody in the disturb ed mothers.