Identification of oilseed rape (Brassica napus) pollen profilin as a cross-reactive allergen.
BACKGROUND
Major allergens of oilseed rape (OSR) pollen with molecular weights of 6/8, 14 and between 27 and 69 kD have been described. The aim of the present study was to further characterize the 14-kD allergen.


METHODS
The 14-kD protein was purified from OSR pollen extracts by poly-(L-proline) (PLP)-Sepharose affinity chromatography and characterized immunologically by means of allergic patients' IgE antibodies, profilin-specific rabbit antisera, Western blot and ELISA inhibition using recombinant birch profilin (rBet v 2), and skin prick testing.


RESULTS
By PLP affinity chromatography, OSR pollen profilin was purified as a single protein of 14.5 kD and further identified as a profilin by three polyclonal rabbit antisera raised against ragweed and tobacco pollen profilin and the C-terminus of birch profilin. IgE binding of a human serum pool (n = 15) and four profilin-reactive sera to nitrocellulose-blotted OSR profilin was completely inhibited by 1 microg/ml rBet v 2 (birch profilin). Reciprocal ELISA inhibition using increasing concentrations of rBet v 2 and purified OSR profilin, respectively, showed that rBet v 2 strongly inhibits antibody binding to OSR profilin, whereas almost 100 times the amount of OSR profilin was needed to inhibit IgE binding to rBet v 2. Skin prick tests were positive (wheal >/=3 mm) with 5 microg/ml rBet v 2 in all three patients tested, and with OSR profilin in two patients at a concentration of 50 microg/ml.


CONCLUSIONS
OSR pollen profilin shares IgE and IgG epitopes with Bet v 2 and other plant profilins and may represent a potentially relevant allergen for profilin-sensitized patients.
FAZ - Floridsdorf Allergy Centre, University of Vienna, Vienna, Austria. science@faz.at
Margarete
M
Focke
W
W
Hemmer
R
R
Valenta
M
M
Götz
R
R
Jarisch
D015153:Blotting, Western; D029688:Brassica napus / Q000276:immunology*; D002847:Chromatography, Agarose; D003285:Contractile Proteins; D003429:Cross Reactions / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D008840:Microfilament Proteins / Q000276:immunology* / Q000302:isolation & purification; D011058:Pollen / Q000737:chemistry / Q000276:immunology*; D051304:Profilins; D012882:Skin Tests
D003285:Contractile Proteins; D008840:Microfilament Proteins; D051304:Profilins; D007073:Immunoglobulin E