Identification of four novel potato (Solanum tuberosum) allergens belonging to the family of soybean trypsin inhibitors.
BACKGROUND
We have previously identified patatin (Sol t 1) of potato tubers as a major food allergen among atopic children. In addition to Sol t 1, concomitant IgE binding to other, then unidentified, potato proteins was observed.


METHODS
Purification and identification of the putative allergens were done by both standard and advanced methods of protein chemistry. The patient series comprised 39 children with positive skin prick test (SPT) to raw potato. Immunoblotting and ELISA were used to examine IgE-binding ability and skin prick testing to assess in vivo reactivity of the purified potato proteins.


RESULTS
Four IgE-binding potato proteins with molecular masses ranging from 16 to 20 kDa were purified and identified as cathepsin D-, cysteine-, and aspartic protease inhibitors belonging to the family of soybean trypsin inhibitors (Kunitz type). The proteins were designated Sol t 2, Sol t 3.0101, Sol t 3.0102, and Sol t 4. In ELISA, 51% of the sera of the 39 atopic children showed specific IgE to Sol t 2, 43% to Sol t 3.0101, 58% to Sol t 3.0102, and 67% to Sol t 4, respectively. All these four allergens were able to produce positive wheal-and-flare responses in SPT.


CONCLUSIONS
In addition to Sol t 1, potato tubers contain several proteins belonging to the family of soybean trypsin inhibitors against which atopic children with positive SPT responses to raw potato have in vitro and in vivo reactive IgE antibodies.
Seppälä
U
U
Institute of Biotechnology, University of Helsinki, Helsinki, National Public Health Institute, Helsinki, Finland.
Majamaa
H
H
Turjanmaa
K
K
Helin
J
J
Reunala
T
T
Kalkkinen
N
N
Palosuo
T
T
D000485:Allergens / Q000009:adverse effects*; D000906:Antibodies / Q000032:analysis / Q000276:immunology; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005512:Food Hypersensitivity / Q000209:etiology*; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000276:immunology; D007223:Infant; D008222:Lymphokines / Q000737:chemistry / Q000302:isolation & purification; D010940:Plant Proteins / Q000276:immunology; D029584:Prostatic Secretory Proteins; D011480:Protease Inhibitors / Q000009:adverse effects / Q000032:analysis / Q000276:immunology; D011198:Solanum tuberosum / Q000737:chemistry / Q000276:immunology*; D014358:Trypsin Inhibitor, Bowman-Birk Soybean / Q000276:immunology*; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000276:immunology*
D000485:Allergens; D000906:Antibodies; D000888:Antibodies, Anti-Idiotypic; D008222:Lymphokines; D010940:Plant Proteins; D029584:Prostatic Secretory Proteins; D011480:Protease Inhibitors; D014358:Trypsin Inhibitor, Bowman-Birk Soybean; C026408:anti-IgE antibodies; C043076:beta-microseminoprotein; C013059:immunoglobulin-binding factors; C060481:CDI protein, Solanum tuberosum; D007073:Immunoglobulin E; D014360:Trypsin Inhibitor, Kunitz Soybean