Background Recent investigation has revealed that spider mites such as Tetranychus urticae and Panonychus ulmi are important allergens in the development of occupational asthma among apple farmers.
Objective To evaluate IgE binding components in T. urticae and P. ulmi-derived crude extracts and their cross-reactivity with Panonychus citri, Tyrophagus putrescentiae and Dermatophagoides pteronyssinus in apple cultivating farmers.
Methods Thirty-one apple farmers with positive skin responses to T. urticae or P. ulmi were randomly recruited, and specific IgE levels in their sera were measured using ELISA. Cross-reactivity was evaluated by ELISA inhibition. IgE binding components were evaluated by IgE immunoblotting.
Results A total of 11 IgE binding components in T. urticae and 10 in P. ulmi were found. Among them, the 17 kDa, 27 kDa, 33 kDa, 37 kDa, 41 kDa, 56 kDa, and 75 kDa allergens in T. urticae, and the 33 kDa, 41 kDa, and 51 kDa allergens in P. ulmi were identified as dominant allergens. T. urticae-specific IgE binding was completely inhibited by 100 μg/mL of T. urticae (99.7%), but only partially inhibited by P. citri (83.0%), P. ulmi (71.6%), T. putrescentiae (69.7%), and D. pternonyssinus (60.1%). P. ulmi-specific IgE binding was completely inhibited by additions of P. citri (92.3%) and P. ulmi (91.2%), but only partially inhibited by the addition of T. urticae (61.5%), T. putrescentiae (57.7%), and D. pteronyssinus (54.4%).
Conclusion There were seven dominant allergens found in T. urticae and three in P. ulmi. T. urticae- and P. ulmi-specific IgE bindings were partially inhibited by crude extracts derived from D. pteronyssinus and T. putrescentiae.