Antigens of Euparipha pisana (snail). I. Identification of allergens by means of in vivo and in vitro analysis.

The data obtained in this study suggest that eating Euparipha pisana (snail), a common food in Mediterranean countries, could give serious allergic reaction such as asthma. We describe here the identification and partial characterization of allergenic molecules form this new source. An aqueous extract of snail was obtained by homogenization in distilled water, centrifugation, dialysis and defatting with ethyl ether. Skin prick test (SPT) performed with the snail extract on 70 subjects allergic to the more common allergens of the Mediterranean area gave a SPT positivity in 61% of the subjects tested, with a mean value of histamine-equivalent prick (HEP) equal to 0.81 +/- 0.25 (n = 43), while no SPT-snail-positive reactions were obtained by using the same extract on 30 not allergic subjects. To ascertain if such a sensitivity was IgE-mediated, sera from SPT-snail-positive subjects were analyzed by RAST, coupling the snail extract to polystyrene balls and to paper discs. 19% of the sera tested were RAST-positive, mean value of binding 4.8 +/- 2.8% (n = 13), while when using sera from SPT-snail-negative subjects, the RAST mean value was 0.49 +/- 0.18% (n = 27). Histamine release (HR) was also performed. Basophils prepared from SPT-snail-positive subjects were incubated with a snail extract. All of the SPT-snail-positive subjects gave a significant value of HR, mean value 21.8 +/- 7% using 1 micrograms of snail extract (n = 16), while 1.41 +/- 1.1% (n = 10) was the mean value obtained when SPT-snail-negative subjects were analyzed.