Sensitization to the major allergen of Brazil nut is correlated with the clinical expression of allergy.
BACKGROUND
Only a few studies have investigated the clinical role of food allergens, especially the relationship between sensitization to a given allergen and occurrence of adverse reactions when eating the relevant food item.


OBJECTIVE
This study evaluated the clinical role of the allergens of Brazil nut by comparing the patterns of IgE binding in sera from 11 patients with anaphylaxis after eating Brazil nuts with those from 10 subjects with no symptoms to this food item. Both groups had specific IgE to Brazil nut.


METHODS
Allergens in the in-house extract of Brazil nut were identified by SDS-PAGE/immunoblotting, the major allergen was purified by HPLC, and its N-terminal sequence was determined by a protein sequencer.


RESULTS
SDS-PAGE/immunoblotting detected a number of allergenic components with molecular weights ranging from 4 to 58 kd. All sera from symptomatic patients recognized a 9-kd allergen corresponding (as established by amino acid sequencing) to a 2S albumin already described as a major allergen of Brazil nut, whereas the other allergens each bound IgE from less than 50% of sera. No sera from asymptomatic subjects showed IgE binding to the 9-kd allergen, but they did recognize components from 25 to 58 kd, which are minor allergens.


CONCLUSIONS
These findings indicate that the allergen underlying clinical reactions to Brazil nut is a 2S albumin of 9 kd and that in vitro reactivity to this allergen identifies subjects who react in vivo to ingestion of this food.
Pastorello
E A
EA
Allergy Center, 3rd Division of General Medicine, Ospedale Maggiore IRCCS, Milan, Italy.
Farioli
L
L
Pravettoni
V
V
Ispano
M
M
Conti
A
A
Ansaloni
R
R
Rotondo
F
F
Incorvaia
C
C
Bengtsson
A
A
Rivolta
F
F
Trambaioli
C
C
Previdi
M
M
Ortolani
C
C
D055516:2S Albumins, Plant; D000293:Adolescent; D000328:Adult; D000418:Albumins / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001667:Binding, Competitive; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005512:Food Hypersensitivity / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D007525:Isoelectric Focusing; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009754:Nuts / Q000009:adverse effects / Q000276:immunology*; D010503:Periodic Acid-Schiff Reaction; D011498:Protein Precursors / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000302:isolation & purification; D017421:Sequence Analysis
D055516:2S Albumins, Plant; D000418:Albumins; D052179:Antigens, Plant; D011498:Protein Precursors; C103364:2S albumin, brazil nut