Skin reactivity and specific IgE sensitization to Tetranychus urticae and identification of IgE binding components

Abstract

Background and ojectives: Tetranychus urticae(TU) is a widely distributed parasitic mite found on fruit trees and green house flowers. A recent investigation demonstrated that TU inhalation causes allergic asthma even in non-farmers. We tried to evaluate skin reactivity and specific IgE sensitization to TU, identify IgE binding components, and evaluate allergenic relationship with house dust mite(HDM). Materials and methods: We carried out skin prick test with TU in 1806 respiratory allergy patients over 1 year living in urban and rural areas. ELISA was performed for detection of specific IgE antibody. To evaluate the cross allergenicity between TU and HDM, ELISA inhibition test was carried out with two kinds of pooled sera: serum pool A included patients' sera sensitized to both TU and HDM, and serum pool B included sera sensitized only to TU. To identify IgE binding components, SDS-PAGE followed by IgE-immunoblot were applied. Results: 358 patients(19.8%) showed positive response(A/H≥2+) on skin prick test. Twelve patients showed isolated positive response to TU. Specific IgE was detected in sixty patients(54.5%) out of 110 sensitized patients. ELISA inhibition test using two sera pools (A and B) showed significant inhibitions by TU with minimal inhibitions by HDM. SDS-PAGE and IgE-immunoblot with patients' individual sera sensitized to both TU and HDM showed 10 IgE binding components (67kD, 29kD, 27kD, 10kD, 14kD, 39kD, 46kD, 35kD, 72kD, 77kD) and two(67kD and 29kD) were bound to IgE in more than 50% of sera tested. In patients' sera sensitized only to TU, nine IgE binding components (67kD, 10kD, 14kD, 29kD, 39kD, 46kD, 72kD, 77kD, 9kD) were found and two(67kD and 10kD) were bound to IgE in more than 50%. Conclusion: Of allergy patients visiting the Allergy Clinic, 19.8% were sensitized to TU and specific IgE was detected in 54.5% of them. No cross allergenicity was noted between TU and HDM. Eleven IgE binding components and three (67kD, 10kD and 29kD) major allergens were identified.