Specific humoral immune responses in 12 cases of food sensitization to sesame seed.

BACKGROUND

Hypersensitivity to sesame seeds is becoming increasingly frequent, probably owing to the larger use of this compound in international food.

OBJECTIVES

This study investigated serum responses of 12 sesame sensitized patients (seven with food allergy, five with food sensitization), to a sesame protein extract, and attempted at identifying sesame major antigens.

METHODS

Sesame protein extracts were prepared from black, white and brown sesame seeds. Electrophoretic analysis showed similar protein patterns in the three extracts, and proper preservation of the proteins integrity. The brown sesame extract was used to set-up an ELISA assay and measure serum levels of antisesame IgG, IgA, IgM and IgE in 12 samples from sesame-sensitized individuals and six controls. It also allowed to perform western blot analyses in order to investigate the molecular weight of sesame proteins recognized by IgG, IgA and IgE.

RESULTS

Nineteen protein bands were observed upon polyacrylamide gel electrophoresis of the sesame protein extracts. Using this whole extract in ELISA, significant antisesame IgG, IgA and IgE-responses were observed in the serum of sensitized individuals, different from the lower signals obtained with control samples. Western blot analysis demonstrated highly polymorphic IgG and IgA responses and a more restricted IgE response pattern, suggesting that two proteins, respectively, 14 kDa and 25 kDa are mostly involved in sesame IgE-dependent hypersensitivity, the 25 kDa band presenting several characteristics of a major allergen.

CONCLUSIONS

This study reports novel information on the possible involvement of a 25 kDa sesame protein in IgE-dependent hypersensitivity to sesame seeds.