IgE, IL4, and soluble FcɛRII in the serum of atopic and nonatopic children

We correlated serum IgE, interleukin 4 (IL4) and soluble low affinity Fc receptor for IgE (sFcɛRII) in atopic and nonatopic children. Serum sFcɛRII was significantly higher in atopic than in nonatopic children (0‐2 yr). Serum sFcɛRII correlated closely with serum IgE in infants, but not in older children. To study further the characteristics of IgE synthesis in infants, we measured the serum level of IL4, which has been demonstrated to enhance the production of both IgE and sFcɛRIIin vitro. Serum IL4 was significantly higher in atopic than in nonatopic infants, but there was no significant difference between atopic and nonatopic older children. These results suggest that IL4 plays an important role in the regulation of IgE synthesis in infants and that IgE synthesis in older children might be modulated by other factors.