Involvement of cross-reactive carbohydrate determinants-specific IgE in pollen allergy testing.
BACKGROUND
Specific IgE antibodies against the low-molecular-weight carbohydrate antigen that does not bridge IgE molecules on mast cells are not associated with clinical symptoms. Cross reactivity can be determined in allergen-specific IgE detection assays when the carbohydrate structures between pollen allergens and plant derived food allergens are similar; in such cases, false positive results for grain or legume allergens can be reported for pollen allergic patients who are not sensitized to those allergens. This phenomenon arises owing to the presence of cross-reactive carbohydrate determinants (CCDs).


OBJECTIVE
This study aimed to assess the impact of CCD interference on the results for pollen allergen-specific IgE antibodies in the general adult population and to perform CCD inhibition tests evaluating the involvement of CCD on samples positive to pollen allergens.


METHODS
Serum samples from 322 subjects were tested for IgE antibodies to pollens and CCD. The research subjects were given questionnaires about pollen allergic symptoms to help assess the presence of allergies. Allergen IgE antibodies for Japanese cedar, Japanese cypress, orchard grass, ragweed, MUXF, bromelain, horseradish peroxidase (HRP), and ascorbate oxidase (ASOD) were analyzed.


RESULTS
It was observed that among individuals who tested positive to any of the pollen allergens, the positive ratio of CCD-specific IgE antibody was the highest for HRP (13.5%-50.0%). The results from the inhibition tests revealed that CCD was marginally present. Although IgE antibodies for cedar pollen did not react with CCD, IgE antibodies for Japanese cypress, orchard grass, and ragweed might be detected by the presence of CCD.


CONCLUSIONS
The results of the inhibition tests revealed the obvious presence of CCD suggesting its involvement. Considering these findings, careful evaluation of patient IgE results should be performed for Japanese cypress, orchard grass, and ragweed.
Department of Otolaryngology-Head and Neck Surgery, Kyorin University School of Medicine, Tokyo 181-8611, Japan.
Hidenori
H
Yokoi
Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Inzai 270-1695, Japan.
Hiroshi
H
Yoshitake
Department of Otolaryngology-Head and Neck Surgery, Kyorin University School of Medicine, Tokyo 181-8611, Japan.
Yuma
Y
Matsumoto
Department of Otolaryngology-Head and Neck Surgery, Kyorin University School of Medicine, Tokyo 181-8611, Japan.
Michitsugu
M
Kawada
SHIDAX Research Institute, Tokyo, Japan.
Yoshiki
Y
Takato
SHIDAX Research Institute, Tokyo, Japan.
Kiyomi
K
Shinagawa
Department of Pharmacology, Kyorin University School of Medicine, Tokyo 181-8611, Japan.
Hiroyuki
H
Sakurai
Department of Otolaryngology-Head and Neck Surgery, Kyorin University School of Medicine, Tokyo 181-8611, Japan.
Koichiro
K
Saito
Allergic rhinitis; Cross-reactive carbohydrate determinants; False positive reactions; Pollen allergy testing; Specific IgE antibodies