Evaluation of IgE reactivity of active and thermally inactivated actinidin, a biomarker of kiwifruit allergy.
Actinidin, an abundant cysteine protease from kiwifruit, is a specific biomarker of isolated allergy to kiwifruit. This study evaluates the IgE-binding properties of biologically active and thermally inactivated actinidin. Employing two different activity assays (caseinolytic assay and zymogram with gelatin) we showed that actinidin obtained from kiwifruit extract under native conditions represents a mixture of inactive and active enzyme. The structural integrity of actinidin was confirmed by SDS-PAGE, Edman degradation, mass fingerprint and Western blot with polyclonal antibodies. Although it was capable of inducing positive skin prick test reactions, we failed to detect IgE reactivity of active actinidin in Western blot with patient sera. Thermally inactivated actinidin exhibited IgE reactivity both in vivo and in vitro, indicating that heat processed kiwifruit products may induce clinical reactivity. These findings imply that apart from the allergenic epitopes on its surface, actinidin also contains hidden epitopes inside the protein which become accessible to IgE upon thermal treatment.
Department of Biochemistry, Faculty of Chemistry, University of Belgrade, and Department of Allergology and Pulmonology, University Children's Hospital, Belgrade 11000, Serbia.
Milica
M
Grozdanovic
Milica
M
Popovic
Natalija
N
Polovic
Lidija
L
Burazer
Olga
O
Vuckovic
Marina
M
Atanaskovic-Markovic
Buko
B
Lindner
Arnd
A
Petersen
Marija
M
Gavrovic-Jankulovic
D000595:Amino Acid Sequence; D015415:Biomarkers / Q000378:metabolism*; D015153:Blotting, Western; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004353:Drug Evaluation, Preclinical; D015180:Electrophoresis, Gel, Two-Dimensional; D005512:Food Hypersensitivity / Q000276:immunology / Q000378:metabolism*; D005638:Fruit / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D008969:Molecular Sequence Data; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D015415:Biomarkers; D007073:Immunoglobulin E; D003546:Cysteine Endopeptidases; C018745:actinidain