Characterization and improvement of apple extracts for the diagnosis of apple IgE-mediated allergy.
BACKGROUND
The production process of reliable fruit extracts is not well established.


OBJECTIVE
To improve the overall quality of apple extracts by reducing protein loss during the manufacturing process and to evaluate the improved extracts using in vivo and in vitro experiments.


METHODS
Two types of extracts were prepared from peels of Golden Delicious apples (Malus domesticus). Extract A was extracted, 1:2 wt/vol, for 30 minutes at 40 degrees C in 0.01 M phosphate-buffered saline, and extract B was extracted, 1:2 wt/vol, in phosphate-buffered saline with 20% polyvinylpolypyrrolidone and 2-mmol/L EDTA. Both extracts were filtered, dialyzed in 3.5-kDa dialysis membranes, and lyophilized. The antigenic and allergenic profiles were analyzed using immunoblot and enzyme-linked immunosorbent assay. Nine patients clinically sensitive to apples and 12 controls underwent skin testing with both extracts.


RESULTS
Extracts A and B had dry weight yields of 0.71% and 1.86% and protein contents of 104.6 and 257 microg/mg of freeze-dried material, respectively. A steady and progressive loss of protein, greater in extract A than in extract B, was detected at different intervals during the manufacturing process of both extracts. Extract B produced larger wheal sizes than extract A (P = .008). Enzyme-linked immunosorbent assay inhibition results confirmed that extract B had a greater inhibition capacity than extract A.


CONCLUSIONS
A progressive loss of protein content occurs during the manufacturing of apple extracts. Wheal sizes induced by extract B were significantly larger than those induced by extract A and prick-by-prick solutions. Extract B was also more potent in vitro than extract A.
Ferrer
Angel
A
Allergy Department, Hospital de la Vega Baja, Orihuela, Alicante, Spain.
Carnés
Jerónimo
J
Gallego
M Teresa
MT
Andréu
Carmen
C
Fernández-Caldas
Enrique
E
D000328:Adult; D000485:Allergens / Q000737:chemistry* / Q000276:immunology; D005260:Female; D005512:Food Hypersensitivity / Q000175:diagnosis* / Q000276:immunology; D005638:Fruit / Q000737:chemistry*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000737:chemistry*; D008297:Male; D027845:Malus / Q000737:chemistry* / Q000276:immunology; D010936:Plant Extracts / Q000737:chemistry / Q000276:immunology; D011506:Proteins / Q000032:analysis; D012882:Skin Tests; D013030:Spain
D000485:Allergens; D010936:Plant Extracts; D011506:Proteins; D007073:Immunoglobulin E