Changes in the mucosal expression of interleukin 15 in Helicobacter pylori-associated gastritis

Transcripts for interleukin (IL) 15 were detected in the gastric mucosal sa mples of 5/5 (100%) patients with no evidence of Helicobacter pylori infect ion and in 4/14 (28%) H. pylori-infected patients (P < 0.05). Both IL-15 mR NA and IL-I5 protein were detected in 1/6 (17%) patients who successfully u nderwent H. pylori eradication therapy, before treatment and in 5/6 (83%) c ases after eradication. Even though a parallel significant (P < 0.03) impro vement of gastritis score occurred after eradication, the severity of gastr itis did not differ according to the mucosal IL-15 expression among H. pylo ri-infected patients, irrespective of the CagA serology. This study demonst rates, for the first time, that transcripts for IL-lj are expressed in the human gastric mucosa. Changes occurring during H. pylori colonisation and a fter eradication raise the hypothesis that H. pylori may downregulate IL-15 expression in the gastric mucosa. (C) 1999 Federation of European Microbio logical Societies. Published by Elsevier Science B.V. All rights reserved.