Detection of a novel 20 kDa shrimp allergen showing cross-reactivity to house dust mites.
BACKGROUND
Allergy to crustacean shellfish is one of the most common IgE-mediated food allergies, and tropomyosin has been identified as the major allergen. However, not all subjects affected by this allergy are IgE-positive to tropomyosin.


OBJECTIVE
To evaluate whether sera of patients with shrimp allergy but negative for tropomyosin react to other allergen(s); and to evaluate the role such allergen(s) may play in cross-reactivity between crustaceans and house dust mites (HDMs).


METHODS
Three different pools of sera-one from subjects with shellfish allergy and HDMs positivity, but negative for recombinant and native tropomyosin (rPen a 1 and nPen m 1) (Pool 2); a second from subjects with tropomyosin and HDMs positivity (Pool 1); and the last from subjects allergic only to HDMs (Pool 3) were submitted to immunoblotting. Subsequently, a 20 kDa protein- enriched fraction of shrimp extract was used at two different concentrations (10 and 100 microg/mL) to pre-absorb the Pool 2 serum and to evaluate, by ELISA assay, the level of inhibition on shrimp and HDMs-coated wells, respectively.


RESULTS
The Pool 2 serum showed IgE reactivity against a 20 kDa component. Its pre-absorption with an enriched fraction of 20 kDa protein caused an inhibition of 56% in IgE binding to shrimp extract at a concentration of 100 microg/mL, and of 14% and 35% to HDMs extract at concentrations of 10 and 100 microg/mL, respectively, as measured by ELISA assay.


CONCLUSIONS
The 20 kDa component seems to be a new crustacean allergen and it could play a role in cross-reactivity with HDMs.
Villalta
D
D
Allergy and Clinical Immunology, A.O. S. Maria degli Angeli, Pordenone, Italy.
Tonutti
E
E
Visentini
D
D
Bizzaro
N
N
Roncarolo
D
D
Amato
S
S
Mistrello
G
G
D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000276:immunology; D002457:Cell Extracts; D003429:Cross Reactions / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000097:blood; D008970:Molecular Weight; D033561:Penaeidae / Q000276:immunology*; D011485:Protein Binding / Q000276:immunology; D011506:Proteins / Q000276:immunology*; D039981:Pyroglyphidae / Q000276:immunology; D012758:Shellfish / Q000009:adverse effects*
D000485:Allergens; D039741:Antigens, Dermatophagoides; D002457:Cell Extracts; C102465:Pen o 1 allergen; D011506:Proteins; D007073:Immunoglobulin E