Usefulness of measurement of antibodies in serum in diagnosis of sensitivity to cow milk and soy proteins in early childhood.

A noteworthy feature of this study is that comparisons were made between specific, sensitive, quantitative measurements of serum antibodies to food proteins and objective appraisal of clinical manifestations by double-blind food challenges. Over 50 children, 4-30 months of age, with suspicious histories of adverse reactions to cow milk or soy products were investigated. Levels of serum antibodies to cow-milk proteins were clearly higher in children with adverse reactions to milk, confirmed by blind challenge; there was no overlap with the lower levels of serum antibodies in children without confirmed reactions. Findings with serial determinations of serum antibodies to cow milk in selected cases are also presented. The levels of serum antibodies evoked by cow milk and soy formulae fed from birth until 4 months of age were similar. The levels of serum antibodies to soy protein in children with and without adverse reactions to soy products were not definitive. The bearing of these data on the comparative "antigenicity" of cow milk and soy products and the distinction between asymptomatic and clinically significant, symptomatic, sensitivity are discussed.