CROSS-REACTIVITY BETWEEN TERRESTRIAL SNAILS (HELIX SPECIES) AND HOUSE-DUST MITE (DERMATOPHAGOIDES-PTERONYSSINUS) - II - IN-VITRO STUDY

Epidemiologic and in vitro data have shown that the association of hou se-dust mite (HDM) allergy and snail allergy in the same patients was due to cross-reactivity between HDM and snail allergenic components. H owever, the cross-reacting allergen(s) have not yet been identified. I n vitro reactivity of seven patients' sera to the various extracts and hemolymph of four different Helix snail species was analyzed by IgE d etection on immunodots and Western blots. Cross-reactivity between sna ils and Dermatophagoides pteronyssinus was assessed by immunodot and E LISA inhibition in two patients. Heterologous inhibition of the snail immunodot and ELISA was observed in one serum. Western blotting showed a specific binding on all four snail species extracts; molecular weig hts of snail allergens ranged from <21 to 200 kDa. Marked individual d ifferences were observed in the seven sera under study; most sera demo nstrated IgE recognition of multiple bands, illustrating that no singl e allergen is responsible for cross-reactivity between snail and mite. These results confirm that cross-reactivity exists between snails of the Helix genus and HDM. This cross-reactivity, involving more than a single allergen, may be of clinical significance in atopic patients al lergic to D. pteronyssinus. The identity of the cross-reacting allerge ns remains to be determined. Potential candidates include the thermost able minor allergens of D. pteronyssinus, tropomyosin and hemocyanin.