Route Of Exposure

Japanese cypress is an evergreen tree native to Japan and found most frequently in Southern Japan and in Taiwan (though it has been exported to many other temperate regions). It is a narrow, loosely conical tree with foliage that ranges from deep blue to bright golden-yellow.

It grows to 40m high and 3m in diameter, with a straight trunk and reddish-brown fibrous bark, fissured into thin strips, and pendulous branches. The tree has a narrow pyramidal crown. The branchlets are slender, closely arranged in a horizontal plane. The closely pressed, scale-like leaves are of 2 sizes and shapes. They have white X-shaped markings underneath. The cones are small and 8-scaled. The yellow-flowered tree is monoecious (having separate male and female reproductive organs on the same plant). It is in flower in May and June

This cypress, rare in natural forests, is in extensive landscape use in Japan and Taiwan. It is found both in mass plantings and in gardens, where dwarf forms are popular. It can be used as a specimen plant, an accent in a border planting, and a "bonsai" tree.

The timber is prized and has often been used in traditional Japanese architecture, in temples and baths as well as homes. It is often the material of furniture and implements.

Clinical Relevance

Allergen description

The following allergens from this plant have been characterised.

Cha o 1 was shown to be composed of 4 components. Molecular masses ranged between 48.5 kDa and 52 kDa. Cry j 1 from Cryptomeria japonica has pectate lyase enzyme activity, suggesting that Cha o 1 may have the same enzyme activity as Cry j 1.

Of patients with pollinosis caused by Japanese cypress tree, 82.5% produced IgE antibodies that were shown to react with purified Cha o 2.

Potential Cross Reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected but in fact does not occur frequently.

Recombinant Cup a 1, the major allergen of Cupressus arizonica pollen, was shown to be highly homologous with the major allergens of Mountain cedar (Jun a 1), Japanese cypress (Cha o 1) and Japanese cedar (Cry j 1). As expected, the high degree of homology with Cha o 1, Jun a 1 and Cry j 1 explains the cross-reactivity of conifer pollens. Different IgE reactivity with the glycosylated and non-glycosylated protein suggests the importance of carbohydrate moieties in the IgE binding site. In a mouse model, the common antigenicity at the T-cell level between Japanese cedar and cypress pollen allergens was demonstrated to be caused by the existence of an identitical-cell epitope in Cry j 1 and Cha o 1. These studies also indicated that Cry j 1 and Cha o 1 share their B-cell epitope but not their T-cell epitope.

A major allergen of Juniperus ashei (Mountain cedar) pollen, Jun a 2, was shown to be highly homologous to Cry j 2 and Cha o 2, the second major allergens of Cryptomeria japonica (Japanese cedar) and Chamaecyparis obtusa (Japanese cypress) pollen, respectively. Mountain cedar and Japanese cypress are members of the same family. The amino acid sequence of Jun a 2 shows 70.7 and 82.0% identity with those of Cry j 2 and Cha o 2, respectively. IgE antibodies in sera of Japanese pollinosis patients were shown to bind not only to Cry j 2 and Cha o 2 but also to Jun a 2, which strongly suggested that allergenic epitopes of the 3 allergens were similar.

The second major allergen from Japanese cypress, Cha o 2, was shown to display a high homology with Cry j 2, the second major allergen of Cryptomeria japonica (Japanese cedar) pollen. The deduced amino acid sequence of Cha o 2 shows 74.3% identity with that of Cry j 2. Cha o 2 shows significant identity with the polygalacturonases of Avocado, Tomato, and Maize as well as Cry j 2.

Because of cross-allergenicity between Cryptomeria japonica (Japanese cedar) and Chamaecyparis obtusa (Japanese cypress) pollen, many Japanese cedar pollinosis patients have symptoms during the cypress pollination season.

Immunotherapy (IT), specific for Japanese cedar pollinosis, reduced the daily symptoms not only in the cedar but also in the cypress pollination season, but not significantly. However, after the season, the mean symptom scores in the IT group tended to be lower than in the non-IT group.

Clinical Experience

IgE-mediated reactions

Japanese cypress may commonly induce symptoms of asthma, allergic rhinitis and allergic conjunctivitis in countries where this tree is common, e.g., Japan. The prevalence of sensitisation to Japanese cypress and Japanese cedar in 267 patients was reported to be 50.1% and 74.7%, respectively. RAST inhibition assays indicated cross-allergenicity between these two pollens and species-specific allergens, which may contribute to the high prevalence of sensitisation to these pollens.

Further studies of sensitisation to Japanese cypress have also reported high levels of sensitisation. Of 934 patients born and raised in an area of Matsusaka, Japan, with nose and/or throat allergies, 35.2% demonstrated specific IgE to Japanese cedar pollen in their serum, and 23.2% for cypress pollen. In 232 ENT patients in Tokyo, positive serum-specific IgE for Japanese cypress was demonstrated in 64.7%. In 267 patients with allergic rhinitis, serum-specific IgE determination demonstrated raised specific IgE to Japanese cypress in 50.6%.