Lipid transfer protein: a pan-allergen in plant-derived foods that is highly resistant to pepsin digestion.
BACKGROUND
Lipid transfer proteins (LTPs) are small molecules of approximately 10 kD that demonstrate high stability. They have recently been identified as allergens in the Rosaceae subfamilies of the Prunoideae (peach, apricot, plum) and of the Pomoideae (apple). They belong to a family of structurally highly conserved proteins that are also present in non-Rosaceae vegetable foods.


OBJECTIVE
The aim of this study was to investigate the cross-reactivity to non-Rosaceae LTPs, and to study the role of protein stability in allergenicity.


METHODS
Thirty-eight patients with a positive SPT to Rosaceae fruit extracts enriched for LTP were characterized by interview and SPT. To investigate IgE cross-reactivity between Rosaceae and non-Rosaceae LTPs, RAST and RAST inhibition as well as ELISA and ELISA inhibition were performed, using whole food extracts and purified LTPs. Both purified natural LTPs (peach, carrot and broccoli) and Pichia pastoris recombinant LTPs (carrot and wheat) were included. Pepsin digestion was used to address the role of stability in the allergenicity of LTPs.


RESULTS
IgE antibodies to Rosaceae LTPs reacted to a broad range of vegetable foods, including Gramineae (cereals), Leguminosae (peanut), Juglandaceae (walnut), Anacardiaceae (pistachio), Brassicaceae (broccoli), Umbelliferae (carrot, celery), Solanaceae (tomato), Cucurbitaceae (melon), and Actinidiaceae (kiwi). Binding and inhibition studies with purified natural and recombinant LTPs confirmed their role in this cross-reactivity. Many of these cross-reactivities were accompanied by clinical food allergy, frequently including systemic reactions. Antibody binding to LTP was shown to be resistant to pepsin treatment of whole extract or purified LTP.


CONCLUSIONS
LTP is a pan-allergen with a degree of cross-reactivity comparable to profilin. Due to its extreme resistance to pepsin digestion, LTP is a potentially severe food allergen.
Asero
R
R
Ambulatorio di Allergologia, Ospedale Caduti Bollatesi, Bollate, Italy.
Mistrello
G
G
Roncarolo
D
D
de Vries
S C
SC
Gautier
M F
MF
Ciurana
C L
CL
Verbeek
E
E
Mohammadi
T
T
Knul-Brettlova
V
V
Akkerdaas
J H
JH
Bulder
I
I
Aalberse
R C
RC
van Ree
R
R
D000293:Adolescent; D000485:Allergens / Q000145:classification* / Q000378:metabolism; D052179:Antigens, Plant; D002352:Carrier Proteins / Q000276:immunology* / Q000378:metabolism; D003429:Cross Reactions; D004063:Digestion; D005512:Food Hypersensitivity / Q000209:etiology / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D019684:Magnoliopsida / Q000276:immunology; D010434:Pepsin A / Q000378:metabolism; D010940:Plant Proteins / Q000276:immunology* / Q000378:metabolism; D011058:Pollen / Q000276:immunology; D019685:Rosales / Q000276:immunology; D012882:Skin Tests
D000485:Allergens; D052179:Antigens, Plant; D002352:Carrier Proteins; D010940:Plant Proteins; C511920:lipid transfer proteins, plant; D007073:Immunoglobulin E; D010434:Pepsin A