Allergenicity of goat's milk in children with cow's milk allergy

Background: Cow's milk allergy (CMA) is a common disease of infancy and childhood. An appropriate cow's milk (CM) substitute is necessary for feeding babies with CMA. CM substitutes are soy formulas and casein- or whey-based extensively hydrolyzed formulas. In several countries, including Italy, goat's milk (GM) formulas are available, and some physicians recommend them for feeding babies with CMA. Objective: We sought to investigate, in vitro and in vivo, the allergenicity of GM in 26 children with proven IgE-mediated CMA. Methods: All the children underwent skin tests with CM and GM; detection of specific serum IgE to CM and GM; and double-blind, placebo-controlled, oral food challenges (DBP-COFCs) with fresh CM, GM, and, as placebo, a soy formula (Isomil, Abbott, Italy), CAP inhibition and immunoblotting inhibition assays were also carried out in 1 of 26 and 4 of 26 children with positive RAST results to both CM and GM, respectively. Results: All the children had positive skin test responses and CAP results to both CM and GM, all had positive DBPCOFC results to CM, and 24 of 26 had positive DBPCOFCs to GM. In CAP inhibition tests, preincubation of serum with CM or GM strongly inhibited IgE either to CM or to GM, In immunoblotting inhibition assays, preincubation with CM completely extinguished reactivity to GM, whereas GM partially inhibited reactivity to CM. Conclusions: These data strongly indicate that GM is not an appropriate CM substitute for children with IgE-mediated CMA. A warning on the lack of safety of GM for children with CMA should be on the label of GM formulas to prevent severe allergic reactions in babies with CMA.