Allergenic characterization of Tyrophagus putrescentiae using sera from occupationally exposed farmers

Background: Allergic sensitivity to storage mites is common in farmers and others who work in environments where hay and grain are handled, stored, or processed. The clinical importance of storage mite-induced allergy in these individuals is generally unknown in the United States. Tyrophagus putrescentiae is a common storage mite, the allergenicity of which has not been characterized. Objective: The purpose of this study was to characterize the allergenicity of Tyrophagus putrescentiae. Methods: Crossed immunoelectrophoresis (CIE) and crossed radioimmunoelectrophoresis (CRIE) were performed to characterize the allergens of this mite using the sera from 24 occupationally exposed farmers RAST-positive to T. putrescentiae. Results: CRIE analysis of T. putrescentiae extract utilizing individual farmers' sera identified 14 allergens. The number of allergens that bound IgE in the individual sera ranged from 5 to 11. Sensitivity to the different allergens varied both within and between patients but 100% of the farmers' sera recognized the same five allergens precipitated by CIE. Fifty percent of patients' sera recognized one additional. Forty-two and 21% of the sera had IgE binding to six and seven of the allergens, respectively. Conclusions: The results of this study showed that farmers who were occupationally exposed to storage mites had serum IgE specific for many potent allergens from T. putrescentiae. Persons who are exposed to stored product mites in occupational settings or by consumption of food containing these mites are therefore at risk of sensitization and allergic reaction. Increased awareness of sensitivity to this mite in the United States' population is needed.