Identification and characterization of a group 2 conifer pollen allergen from Chamaecyparis obtusa, a homologue of Cry j 2 from Cryptomeria japonica.
BACKGROUND
Not only Cryptomeria japonica (Japanese cedar) pollen but also that of Chamaecyparis obtusa (Japanese cypress) induces the allergic symptoms of Japanese cedar pollinosis. However, allergens from C. obtusa pollen have not been as well characterized as those from C. japonica pollen.


OBJECTIVE
We sought to identify and characterize a homologue of the second major allergen of C. japonica pollen, Cry j 2, from the pollen of C. obtusa.


METHODS
An allergen homologous to Cry j 2 was identified in C. obtusa pollen extract by immunoblot analysis, probed with anti-Cry j 2 monoclonal antibodies and purified by a series of column chromatographic steps.


RESULTS
The allergen isolated from the extract showed a slightly diffuse band of 45 kDa and closely spaced double-bands of 42 and 45 kDa on SDS-PAGE, under reducing and non-reducing conditions, respectively; the bands were approximately 5-7 kDa larger than those of Cry j 2. In 24 of 30 residues, the N-terminal amino acid sequence of the allergen was identical with corresponding sequence in Cry j 2. Most patients with pollinosis who were IgE antibody-positive to Cry j 2 were shown to be IgE antibody-positive to this allergen, and the IgE antibody levels to both allergens were highly correlated.


CONCLUSIONS
The results indicate that the allergen isolated from C. obtusa pollen in this study is a homologue of Cry j 2. The allergen was designated as Cha o 2 according to the WHO/IUIS Allergen Nomenclature Subcommittee recommendation.
Yasueda
H
H
Clinical Research Center for Allergy and Rheumatology, National Sagamihara Hospital, Japan.
Saito
A
A
Sakaguchi
M
M
Ide
T
T
Saito
S
S
Taniguchi
Y
Y
Akiyama
K
K
Inouye
S
S
D000485:Allergens; D010940:Plant Proteins / Q000032:analysis* / Q000276:immunology; D011058:Pollen; D013045:Species Specificity
D000485:Allergens; C065291:Cry j II protein, Cryptomeria japonica; D010940:Plant Proteins