Gastric mucosal mast cells in atopic subjects

Intragastral allergen provocation under endoscopic control (IPEC) allows direct observation of gastric mucosa reactions after contact with inhalant allergens that reach the stomach. We selected patients with proved atopy to Parietaria but without clinical and endoscopic signs of gastric disease, and we tested them with the specific inhalant allergen during IPEC, recording gastric macroscopic reaction and mucosal mast-cell changes in biopsy specimens. All atopic patients showed visible changes in gastric mucosa quantified as IPEC score. Mast-cell numbers detected in atopic patients (135.4 +/- 102.6/mm2 of stromal area) were significantly higher than in nonatopic subjects (59.8 +/- 25.4/mm2; P < 0.03) and were positively correlated to atopic IPEC score (P < 0.01). In addition, 6/12 atopics who had both higher mast-cell counts and IPEC score showed an intraepithelial distribution of gastric mast cells which displayed ultrastructural features of partial degranulation. It is likely that changes observed in our patients with allergy to Parietaria reflect a subclinical activation of mast cells in the gastric mucosa.