Allergenic molecules
Allergens in storage mites include fatty acid-binding proteins, tropomysin and paramyosin homologues, apoliphorine-like proteins, alfa tubulines and other allergens, such as group 2, 5 and 7 allergens (9). Studies have identified at least 20 allergenic molecules from extracts of L. destructor (9). One of these molecules, Lep d 2, is considered a major allergen (15 kDa) which showed high IgE reactivity both in vitro and in vivo. Lep d 2 also presents a high degree of polymorphism, with variants that may differ between wild and cultured mite populations (9). Other antigens include: Lep d 5, a molecule of unknown function, that could bind antibodies from 9% serum in study of 45 patients. Lep d 7, which in recombinant form was recognized by IgE in 62% of L. destructor sensitized patients. Lep d 10, which showed in its recombinant version binding to 13% of serum samples from patients sensitized to mites and/or crustaceans. Lep d 13, an intracellular lipid transport protein, could bind 13% of serum samples from sensitized patients when presented in recombinant form. Lep d 33, an α-tubulin, recognized 12% of serum samples from sensitized patients. Finally a 39kDa protein of unknown function showed 46.5% binding to serum of farmers sensitized to L. destructor (9). Other antigens named Lep d 3, 8 and 12 have also been identified (9).
Table adapted from Allergome.org (10):
Cross-reactivity
Allergenic cross-reactivity between storage mites and HDMs is well documented; in a European Community Respiratory Health Survey, 8% of people were found to be sensitized to HDMs and 10% to storage mites. Among those patients with storage mite sensitization, 44% were also sensitized to HDM (4).
Another study reported that 88.4% (n/N=274/310) of patients sensitive to house dust mites were also sensitive to storage mites; 73% (n/N=227/310) of patients were sensitized to all three species of storage mite studied (L. destructor, Tyrophagus putrescentiae and Acarus. siro) (11).
