Identification and immunologic characterization of an allergen, alliin lyase, from garlic (Allium sativum).
BACKGROUND
Garlic (Allium sativum) is one of the most common relishes used in cooking worldwide. Very few garlic allergens have been reported, and garlic allergy has been rarely studied.


OBJECTIVE
The aim of the study was to identify allergenic proteins in garlic and to investigate their importance in allergies to other Allium species (leek, shallot, and onion).


METHODS
A crude extract of garlic proteins was separated by SDS-PAGE and 2-dimensional electrophoresis; immunoblotting was then performed with the use of individual and pooled sera from patients with garlic allergy, and the major IgE-binding proteins were analyzed by amino acid sequencing and mass spectrometry. The putative allergens were further purified by chromatography; the antigenicity, allergenicity, and IgE-binding cross-reactivity of the purified protein were then studied by immunoblotting, periodate oxidation, skin tests, and IgE-binding inhibition assays.


RESULTS
A major allergen, alliin lyase, was identified by mass spectrometry and Edman sequencing and purified to homogeneity through the use of a simple 2-step chromatographic method. Skin tests showed that the purified protein elicited IgE-mediated hypersensitive responses in patients with garlic allergy. Periodate oxidation showed that carbohydrate groups were involved in the antigenicity, allergenicity, and cross-reactivity. Garlic alliin lyase showed strong cross-reactivity with alliin lyases from other Allium species, namely leek, shallot, and onion.


CONCLUSIONS
Alliin lyase was found to be a major garlic allergen in a garlic-allergic group of patients in Taiwan. The wide distribution of alliin lyase in Allium suggests it may be a new cross-reactive allergen.
Kao
Shao-Hsuan
SH
Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Hsu
Ching-Hsian
CH
Su
Song-Nan
SN
Hor
Wei-Ting
WT
Chang T
Wen-Hong
WH
Chow
Lu-Ping
LP
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D000596:Amino Acids / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis; D013437:Carbon-Sulfur Lyases / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism; D002648:Child; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005512:Food Hypersensitivity / Q000453:epidemiology / Q000209:etiology; D005737:Garlic / Q000201:enzymology*; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D012882:Skin Tests
D000485:Allergens; D000596:Amino Acids; D002241:Carbohydrates; D007073:Immunoglobulin E; D013437:Carbon-Sulfur Lyases; C019243:alliin lyase