Cord serum IgE in relation to family history and as predictor of atopic disease in early infancy.

Cord serum IgE was assayed by particle counting immunoassay (PACIA) in an unselected series of European newborns (n = 190; geom mean = 0.37 IU/ml) and a cut-off limit established (greater than or equal to 1.20 IU/ml) for prediction of atopy. At control follow-up by questionnaire 18 months after birth, 38 infants (20.0%) had developed definite (9.5%) or probable (10.5%) atopy with a significant predominance of boys (P less than 0.03). Infants with a positive immediate family history (IFH) had a higher risk of developing atopy (P less than 0.0025) and also had a higher incidence of elevated cord IgE (P less than 0.02) than infants with a negative IFH. Maternal atopy influenced cord IgE levels significantly (P less than 0.00005), whereas paternal atopy did not (P = 0.23). No fetal IgE antibodies against five common allergens could be demonstrated in 36 cord sera tested. Breast-feeding for 3 months was not sufficient to prevent atopic symptoms. The predictive value of cord IgE was high since 26 of 36 newborns (positive predictive value = 72.2%) with elevated cord IgE had developed atopic symptoms before follow-up. Of the 38 infants who developed atopic symptoms, 26 had elevated cord IgE (sensitivity = 68.4%) compared to only 10 (6.6%) of the 152 atopy-free infants (P less than 0.00005). The data indicate that elevated cord IgE as determined by PACIA is a good predictor of early-onset atopy, better than family history (P less than 0.008), and that primarily maternal atopy seems to affect fetal IgE synthesis.