Allergenic components of a novel food, Micronesian nut Nangai (Canarium indicum), shows IgE cross-reactivity in pollen allergic patients.
BACKGROUND
New foods may present a risk for food hypersensitive patients. Several examples exist of allergic reactions caused by cross-reactive plant-derived foods, and new foods should be scrutinised before introducing them to the market. We have evaluated the clinical and serological relevance of cross-reactivity between Nangai and pollen allergens.


METHODS
Cross-reactivity was examined with Maxisorp RAST (radioallergosorbent test), RAST inhibition and Western blot, using sera from patients allergic to grass, birch and mugwort pollen. None of the patients reported having seen or eaten Nangai previously. To determine the biological and clinical relevance of the cross-reactivity, histamine release (HR) test, skin prick test (SPT) and food challenge were used.


RESULTS
There was prevalence for reactivity against Nangai in the group of pollen allergic patients. This cross-reactivity seems to be related--at least in part--to carbohydrate epitopes. Three out of 12 patients tested with Nangai were positive upon open challenge, but using double blind placebo controlled food challenge (DBPCFC) this could not be confirmed in two patients. The biological effects of Nangai on allergic patients were confirmed using HR and SPT.


CONCLUSIONS
The Nangai specific IgE found among pollen allergic patients addresses the need for control of new or changed foods before introduction to the market.
Sten
Eva
E
Allergy Unit TTA 7542, National University Hospital, 2200 Copenhagen, Denmark.
Stahl Skov
P
P
Andersen
S B
SB
Torp
A M
AM
Olesen
A
A
Bindslev-Jensen
U
U
Poulsen
L K
LK
Bindslev-Jensen
C
C
D000485:Allergens / Q000008:administration & dosage / Q000009:adverse effects*; D000818:Animals; D000918:Antibody Specificity / Q000276:immunology; D000943:Antigens, Differentiation / Q000032:analysis / Q000276:immunology; D001667:Binding, Competitive / Q000276:immunology; D002415:Cats; D003429:Cross Reactions / Q000276:immunology*; D004285:Dogs; D004306:Dose-Response Relationship, Immunologic; D004311:Double-Blind Method; D004591:Electrophoresis, Polyacrylamide Gel; D037502:Galectin 3; D006636:Histamine Release / Q000276:immunology; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000209:etiology*; D015151:Immunoblotting; D016056:Immunodominant Epitopes / Q000276:immunology; D007073:Immunoglobulin E / Q000276:immunology; D021184:Nut Hypersensitivity / Q000209:etiology*; D009754:Nuts / Q000009:adverse effects*; D010936:Plant Extracts / Q000008:administration & dosage / Q000009:adverse effects; D011058:Pollen / Q000009:adverse effects*; D011852:Radioallergosorbent Test; D012680:Sensitivity and Specificity; D012882:Skin Tests
D000485:Allergens; D000943:Antigens, Differentiation; D037502:Galectin 3; D016056:Immunodominant Epitopes; D010936:Plant Extracts; D007073:Immunoglobulin E