Background and objective: Previous investigations demonstrated that two-spotted spider mite (TSM) inhalation causes allergic asthma in agricultural workers. This work investigates whether TSM causes similar problems in the urban population. We determined the sensitization rate to TSM. We also identified immunoglobulin (Ig)E-binding components and evaluated their relationship with house-dust mite (HDM) allergens.
Methods: We carried out skin prick test (SPT) with TSM in 1,806 respiratory allergy patients over 1 year. TSM-IgE was detected by enzyme-linked immunoadsorbent assay (ELISA). TSM-sensitized patients were classified into two groups: patients who were skin test-positive to both TSM and HDM were included in group A and patients who were skin test-positive to TSM only were included in group B. ELISA inhibition test using sera from group A and B were conducted. IgE-immunoblotting was used to identify major allergens. These were purified by 2-dimensional electrophoresis and blotted onto polyvinylidene difluoride, and N-terminal sequences were identified.
Results: SPT (> or = 2+ of allergen/histamine) was positive in 358 (19.8%) patients. Twelve (6.6%) showed positive response to TSM only, and 54.5% had positive specific IgE. ELISA inhibition test using sera from two groups showed significant inhibition by TSM with minimal inhibition by HDM. Amino acid sequence of three major allergens was not homologous with any previously characterized allergens.
Conclusion: IgE-sensitization rate to TSM was 19.8% in respiratory allergy patients. Eleven IgE-binding components and three major allergens were identified. The pIs and amino acid sequences of the major allergens were determined.