The effect of thermal processing on the IgE reactivity of the non-specific lipid transfer protein from apple, Mal d 3.
BACKGROUND
Non-specific lipid transfer proteins (LTPs) are involved in allergy to fresh and processed fruits. We have investigated the effect of thermal treatment and glycation on the physico-chemical and IgE-binding properties of the LTP from apple (Mal d 3).


METHODS
Mal d 3 was purified from apple peel and the effect of heating in the absence and presence of glucose investigated by CD spectroscopy, electrospray and MALDI-TOF mass spectrometry. IgE reactivity was determined by RAST and immunoblot inhibition, SPT and basophil histamine release test.


RESULTS
The identity and IgE reactivity of purified Mal d 3 was confirmed. Mild heat treatment (90 degrees C, 20 min) in the absence or presence of glucose did not alter its IgE reactivity. More severe heat treatment (100 degrees C, 2 h) induced minor changes in protein structure, but a significant decrease in IgE-binding (30-fold) and biological activity (100- to 1000-fold). Addition of glucose resulted in up to four glucose residues attached to Mal d 3 and only a 2- and 10-fold decrease of IgE-binding and biological activity, respectively.


CONCLUSIONS
Only severe heat treatment caused a significant decrease in the allergenicity of Mal d 3 but glycation had a protective effect. The presence of sugars in fruits may contribute to the thermostability of the allergenic activity of LTP in heat-processed foods.
Sancho
A I
AI
Institute of Food Research, Norwich Research Park, Colney, Norwich, UK.
Rigby
N M
NM
Zuidmeer
L
L
Asero
R
R
Mistrello
G
G
Amato
S
S
González-Mancebo
E
E
Fernández-Rivas
M
M
van Ree
R
R
Mills
E N C
EN
D000485:Allergens / Q000737:chemistry* / Q000276:immunology*; D052179:Antigens, Plant; D002352:Carrier Proteins / Q000737:chemistry / Q000276:immunology; D005512:Food Hypersensitivity / Q000209:etiology / Q000276:immunology*; D006636:Histamine Release; D006358:Hot Temperature; D007073:Immunoglobulin E / Q000097:blood*; D027845:Malus / Q000009:adverse effects / Q000276:immunology*; D010940:Plant Proteins; D011489:Protein Denaturation; D012882:Skin Tests
D000485:Allergens; D052179:Antigens, Plant; D002352:Carrier Proteins; C463180:Mal d 3 allergen; D010940:Plant Proteins; C511920:lipid transfer proteins, plant; D007073:Immunoglobulin E