The source of immunoglobulin E in the fetus at term

A high level of immunoglobulin E (IgE) in cord blood (CB) is well known to be predictive of the development of clinical allergy during early childhood. We have tried to ascertain the source of IgE in cord blood by carrying out a series of measurements of IgE concentrations in arterial and venous CB of newborns and comparing them to IgE concentrations in blood samples from both parents. We found that the concentrations of IgE in arterial and venous CB were almost completely identical in the 131 newborns examined whereas IgD concentrations were significantly higher in arterial than in venous CB. Moderate but significant positive correlations were found between IgE concentrations in maternal blood and CB; paternal blood and CB; and maternal and paternal blood. Our data suggest that CB-IgE is essentially a product of fetal lymphocytes. The positive correlations found between the IgE blood concentrations in the newborns, the mothers and the fathers, is most likely an effect of the amount and nature of the allergenic constituents in the family environment.