Effects of Structure Modifications on IgE Binding Properties of Serum Albumins

Abstract

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.

Antigenic Determinants of Bovine Serum Albumin

“…In contrast, previous studies by our group showed that serum albumin antigenicity is only partially correlated with its native three-dimensional structure [8]. …”

“…After polyacrylamide gel electrophoresis (PAGE), immunoblotting was performed as described by Restani et al [8]. …”

“…Patients allergic to animal’s hair/dander normally react to the serum albumin of the correlated species; subjects allergic to cows often react to BSA [4, 5]. In our previous studies, BSA was also identified as one of the most important allergens in bovine meat as shown by skin prick test, immunoblotting and double-blind placebo-controlled food challenge (DBPCFC) [6, 7, 8]. …”

“…We showed in previous studies that circulating IgEs specific for BSA (from sera of allergic children) were able to cross-react with albumins from sheep and pig, but they did not recognize those of horse, rabbit, turkey and chicken [8]. We hypothesized that the BSA antigenic determinant for human antibodies is localized in the sequence 520–542, where important differences in the amino acid sequence are identifiable between cross-reacting and non-cross-reacting serum albumins.…”

Kinetic and thermodynamic analysis of ultra-high pressure and heat-induced denaturation of bovine serum albumin by surface plasmon resonance

“…It has been reported that allergy to meat is rare; positive skin prick tests to beef were described in only 7.69 % of children with atopic dermatitis [3,4]. However, BSA has been identified as one of the most important allergens in bovine meat, with a high degree of crossreactions due to the significant sequence and structural similarities of serum albumin from different organisms [5,6]. In recent years, ultrahigh pressure (UHP) has been more frequently applied instead of traditional thermal treatment, especially for pasteurization [7].…”