IgE cross-reactivity with caseins from different species in humans allergic to cow's milk

Fifty-eight sera from humans allergic to cow's milk proteins were analysed for the specificity of their IgE response to the whole casein fraction of m ilk from different ruminant and non-ruminant species (e.g. cow, sheep, goat , rabbit and mt). IgE-specific responses were determined by an enzyme aller gosorbent test using the purified casein fractions as immobilized antigen a nd an anti-human IgE monoclonal antibody labelled with acetylcholinesterase . Go-and/or cross-sensitizations to caseins of the different ruminant speci es occurred extensively, though IgE responses to ovine and caprine casein a ppeared to be lower than that obtained with bovine casein. Cross-reactivity is suggested by the significant reactivity of rat and rabbit casein toward human IgE In terms of specificity and intensity, the IgE response to casei ns demonstrates a great variability. Structural homologies in caseins of su ch different species, that can share common epitopes for the IgE of some pa tients, suggest that prevention of cow's milk allergy cannot be achieved by using milk from other:species as substitutes.