Effects of structure modifications on IgE binding properties of serum albumins.

BACKGROUND: Bovine serum albumin (BSA) is one of the most widely studied proteins; its structure is well-known and its antigenic characteristics have been described in studies performed in in vitro and animal models. The aim of our work was to evaluate the role of BSA conformation in its antigenicity (recognition by circulating IgEs from allergic children).
METHODS: This study was performed using electrophoresis associated with the immunoblotting technique, where sera from children sensitized to BSA (as shown by double-blind placebo-controlled food challenge) were used. RESULTS AND DISCUSSION: Heat treatment and chemical denaturation (SDS treatment) are not able to decrease the BSA capability to bind circulating IgEs. Only by reducing treatment with 2-mercaptoethanol is it possible to modify but not to eliminate the antigenicity of this protein. The reactivity to other serum albumins from different animal species was also investigated and in this study we show a direct correlation between the number of IgE-mediated responses observed in immunoblotting and the percentage of sequence identity (phylogenetic similarity) of serum albumins.
CONCLUSION: Data obtained in this research indicate that serum albumin antigenicity is only partially correlated to its native three-dimensional structure.