The use of aluminum hydroxide as adjuvant modulates the specific antibody response - a Brown Norway rat study with native and denatured cow's milk allergens

There is a need for efficient methods to treat food allergy, however, no immunotherapeutic method has yet been satisfactory due to the high rate of unpredictable severe reactions and the limited efficacy. Therefore, modified versions of food allergens have been suggested as alternatives to the parent proteins for immunotherapy. The aim of the study was to compare the inherent allergenicity of the native and denatured version of the cow's milk proteins β-lactoglobulin and α-lactalbumin, and to study the impact of the use of Al(OH)3 as an adjuvant. Brown Norway rats were immunised intraperitoneally with either native or denatured β-lactoglobulin or α-lactalbumin, with or without the use of Al(OH)3 as adjuvant. Antibody responses were analysed in various ways by means of different ELISAs. Both the immunogenicity and the sensitising capacity of the cow's milk allergens were influenced by their globular folding, with the native version being more allergenic than the denatured counterpart. The native folded proteins mainly raised antibodies against conformational epitope, whereas the denatured versions predominantly raised antibodies against linear epitopes. Most interestingly, the study showed that the use of Al(OH)3 , besides increasing immunogenicity and sensitising capacity of the cow's milk allergens, caused a modification of the specificity of the antibodies raised against the native version of the proteins. Adsorption of the native forms of the allergens to Al(OH)3 caused a significant greater proportion of antibodies raised against linear epitopes, stressing that the adsorption induced a partly unfolding of the proteins. This may have implications for IT safety and efficacy.