A method for estimation of circulating immune complexes after oral challenge with ovalbumin.

Sera from forty-two children orally challenged with ovalbumin were analysed for the presence of IgG-ovalbumin immune complexes. The technique used is based on the absorption of the IgG of the complex to immobilized protein-A and detection of the ovalbumin of the complex on the solid phase, using isotope-labelled, pepsin-digested antibodies to ovalbumin. Children with high serum levels of antibody to ovalbumin had significantly higher concentrations of IgG-ovalbumin complexes that children with low antibody levels. In both groups the appearance of the complexes in the serum was accompanied by a significant decrease of the complement factor C3 (P < 0.05). The duration of the decrease in C3 was correlated to the amount of IgG-ovalbumin complexes, suggesting a consumption of C3 by these immune complexes.