Cross-reactivity within the profilin panallergen family investigated by comparison of recombinant profilins from pear (Pyr c 4), cherry (Pru av 4) and celery (Api g 4) with birch pollen profilin Bet v 2.
Profilin is a panallergen which is recognised by IgE from about 20% of birch pollen- and plant food-allergic patients. Little is known about epitope diversity among these homologous proteins, and about the correlation between IgE-cross-reactivity and allergenic reactivity. Plant food profilins from pear (Pyr c 4) and cherry (Pru av 4) were cloned by polymerase chain reaction and produced in Escherichia coli BL21. The profilins were purified as non-fusion proteins by affinity chromatography on poly-(L-proline)-Sepharose and characterized by immunoblotting, IgE-inhibition experiments and histamine release assays. The coding regions of the cDNA of pear and cherry profilin were identified as a 393 bp open reading frame. The deduced amino acid sequences showed high identities with birch pollen profilin Bet v 2 (76-83%) and other allergenic plant profilins. Pyr c 4 and Pru av 4 were investigated for their immunological properties in comparison with profilins from celery (Api g 4) and birch pollen (Bet v 2). Fourty-three of 49 patients (88%), preselected for an IgE-reactivity with Bet v 2 showed specific IgE-antibodies to the recombinant pear protein, 92% of the sera were positive with the recombinant cherry allergen and 80% of the sera were reactive with the celery protein. Inhibition experiments showed a strong cross-reactivity of IgE with profilins from plant food and birch pollen. However, IgE binding profiles also indicated the presence of epitope differences among related profilins. All investigated profilins, Pyr c 4, Pru av 4, Api g 4 and Bet v 2, presented almost identical allergenic properties in cellular mediator release tests. Therefore, cross-reactivities between related profilins may explain pollen-related allergy to food in a minority of patients. The nucleotide sequences reported have been submitted to the Genbank database under accession numbers AF129424 (Pyr c 4) and AF129425 (Pru av 4).
Scheurer
S
S
Department of Allerology, Paul-Ehrlich-Institut, Langen, Germany.
Wangorsch
A
A
Nerkamp
J
J
Skov
P S
PS
Ballmer-Weber
B
B
Wüthrich
B
B
Haustein
D
D
Vieths
S
S
D000485:Allergens / Q000276:immunology* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003285:Contractile Proteins; D003429:Cross Reactions; D017931:DNA Primers; D018076:DNA, Complementary; D006636:Histamine Release; D006801:Humans; D008840:Microfilament Proteins / Q000276:immunology* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D051304:Profilins; D011994:Recombinant Proteins / Q000276:immunology / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid
D000485:Allergens; D003285:Contractile Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D008840:Microfilament Proteins; D051304:Profilins; D011994:Recombinant Proteins