Ippei Takagi

Purification, characterization and molecular cloning of Cha o 1, a major allergen of Chamaecyparis obtusa (Japanese cypress) pollen.

Pollen of Chamaecyparis obtusa (Japanese cypress) is one of the causes of allergic pollinosis in Japan. A major allergen of the pollen designated Cha o 1, was purified by two-step ion exchange chromatography. Cha o 1 was separated into four components with molecular masses of 48.5 kDa and 52.0 kDa, each with pIs of 6.77 and 6.82. The 23-residue N-terminal sequence of Cha o 1 was determined and shown to have high identity with that of Cry j 1, a major allergen of Cryptomeria japonica pollen. cDNA coding for Cha o 1 was cloned by hybridization screening using Cry j 1 cDNA as a probe. One of the cDNA clones, pCHA-1 was sequenced and found to code for a putative 21-residue signal peptide and a 354-residue native protein with a derived molecular mass of 38.1 kDa. The deduced amino acid sequence of Cha o 1 showed 79-80% identity with those of Cry j 1. These findings were consistent with observations of a close crossreaction between the two allergens. Homology analyses revealed that Cha o 1 had 46-49% identity with Amb a 1 families and Amb a 2, the major allergens of short ragweed. Cry j 1 has pectate lyase enzyme activity, suggesting that Cha o 1 may have the same enzyme activity as Cry j 1.

Causative allergens of allergic rhinitis in Japan with special reference to silkworm moth allergen

To determine the importance of silkworm moth allergens, we tested 267 patients with allergic rhinitis with CAP‐RAST®, a new assay system for detecting specific IgE in sera. We used the following allergen sources: house‐dust mite, Candida, Altemaria, cat dander, orchard grass, ragweed, mugwort, Japanese hops, Japanese cedar, Japanese cypress, cotton, silk, larval chironomid midge, adult chironomid midge, and silkworm moth. As expected, the highest positive rate of reaction, as determined by CAP‐RAST, was 73.8% for Japanese cedar, followed by 53.2% for mite and 50.6% for Japanese cypress. Although the positive rate for silkworm moth was not as high as for cedar pollen, one‐third of patients had specific IgE against silkworm moth. The positive rate of reaction to silkworm moth was much higher than that to chironomid. It was interesting to note that the patients reported had not been documented as having frequent contact with silkworm moth allergen. Correlations between silkworm moth and silk, and silkworm moth and chironomid midge were found to be significant (P <0.001). Silkworm moth allergen showed the third highest reaction rate in patients with severe symptoms. These results suggest that silkworm moth allergen should be considered to be important in patients with allergic rhinitis in Japan.