[Habitual vomiting due to dust mite allergy. A case report].

It has been demonstrated that: a) part of the inhalant allergenic particles we normally breath, adhere to the oropharyngeal mucosa, and eventually progress to the gastrointestinal tract; b) digestive tract mucosa is able to produce specific IgE against aeroallergens even before than respiratory tract mucosa. The case is described of a 5-year-old girl who presented a daily vomiting since she was 6 months. All clinical instrumental and laboratory findings had been unable to reach a definite diagnosis. SPT (inhalants and foods): Dermatoph. pteronyssinus: + (confirmed by RAST). The patient had an immediate, complete recover just following the clinician's instruction for HDM domestic prevention. Symptoms appeared again in response to a NPT performed with Dermatophagoides extract. The positivity of the exclusion-re-exposure test confirmed the diagnosis of HDM-induced gastrointestinal allergic syndrome, so far not described in literature (to my knowledge). Immunological considerations: since it is known that patients allergic to HDM do not usually present a specific IgE-mediated gastrointestinal allergic syndrome, it is suspectable that an immunological tolerance can be instaured toward inhalant allergens as it normally happens toward food allergens. In atopic individuals there is a high expression of ICAM-1, VCAM-1 and other adhesion molecules on the surface of HEV at BALT level. Adhesion molecules expression and immunocompetent cells activation are modulated by several mechanisms among which the cytokine network plays a major role. The author speculates that sensitized lymphocytes may migrate from intestinal to bronchial mucosa, via lymphocytic immunoallergic competence. In the described clinical case this mechanism did not work.