Profilin (Che a 2) and polcalcin (Che a 3) are relevant allergens of Chenopodium album pollen: isolation, amino acid sequences, and immunologic properties.
BACKGROUND
Little is known about the molecular properties of chenopod allergens. Recently, profilin and 2 EF-hand calcium-binding protein (polcalcin) have been shown to play a role in chenopod pollinosis.


OBJECTIVE
We sought to analyze these panallergens in chenopod pollen and to evaluate their involvement in the allergy to this biologic source.


METHODS
Profilin and polcalcin were purified to homogeneity and characterized by using spectrometric and chemical methods. Immunologic analyses were performed by means of immunoblotting, ELISA, and competitive inhibition assays with olive profilin- and polcalcin-specific rabbit polyclonal antibodies and sera from patients with chenopod allergy. cDNAs encoding these proteins were cloned by means of PCR and sequenced.


RESULTS
Purified Che a 2 (profilin) and Che a 3 (polcalcin) exhibited prevalences of 55% and 46%, respectively, in patients (n=104) hypersensitive to chenopod pollen. Both purified allergens individually inhibited the IgE binding to the whole pollen extract and showed strong cross-reactivity with the corresponding olive pollen profilin (Ole e 2) and polcalcin (Ole e 3). Chenopod profilin consists of a 131-amino-acid chain that displays identities of approximately 75% and 82% with pollen and food profilins, respectively. Che a 3 (86 amino acids) displays similarity (65% to 82% identity) with polcalcins from pollens of olive, birch, alder, rapeseed, and timothy.


CONCLUSIONS
Profilin and polcalcin are relevant panallergens in chenopod pollen and good candidates to be involved in IgE cross-reactivity with other pollen sources, thus explaining the highly frequent polysensitization of patients allergic to chenopod.
Barderas
Rodrigo
R
Departmento Bioquímica y Biología Molecular, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain.
Villalba
Mayte
M
Pascual
Cristina Y
CY
Batanero
Eva
E
Rodríguez
Rosala
R
D000485:Allergens / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D027463:Chenopodium album / Q000276:immunology*; D003001:Cloning, Molecular; D003285:Contractile Proteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D003429:Cross Reactions; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008840:Microfilament Proteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D011058:Pollen / Q000276:immunology*; D051304:Profilins; D011817:Rabbits
D000485:Allergens; D003285:Contractile Proteins; D008840:Microfilament Proteins; D051304:Profilins; D007073:Immunoglobulin E