Analysis of IgE-binding factors (sCD23) within newborn sera.

Factors are discussed as potential diagnostic parameters of atopic disorders. The amounts of sCD23 in sera from newborn children (n = 4,329) were determined by radioimmunoassay with monoclonal antibodies specific for CD23. The sCD23 levels ranged between 0 and 81.5 ng/ml of CD23-specific mAb. Furthermore, the sera of newborns with more than 5 ng/ml (n = 45) were analyzed by SDS/PAGE and subsequent autoradiography using 125I-labeled IgE (PS). These experiments indicate that newborn sera with normal sCD23 amounts contain an IgE-binding activity with a molecular weight of 25 kD; this component was not observed within sera containing elevated amounts (> 5 ng/ml). In addition, a 60-kD IgE-binding component was detected within most of all newborn sera (76.4%). The data show that the IgE-binding pattern of newborn children and the pattern of adult donors are different. Our data suggest that the measurement of quantitative sCD23 amounts combined with the analysis of the molecular weight pattern of the IgE-binding factors might be a helpful diagnostic parameter with regard to IgE-associated diseases.