AN INCREASED NUMBER OF FOLLICLES CONTAINING ACTIVATED CD69-CELLS AND PROLIFERATING CD71+ B-CELLS ARE FOUND IN H-PYLORI-INFECTED GASTRIC-MUCOSA( HELPER T)

Objective: An immune response occurring in Helico-bacter pylori-infect ed gastric mucosa could have a direct implication for associated patho logies, In the present study we analyzed the expression of the immune activation, proliferation, and phenotype markers by immune cell subpop ulations in H. pylori-infected and uninfected gastric samples. Methods : Antral gastric biopsies from both H. pylori-positive and -negative p atients were processed by immunohistochemistry; gastric epithelial cel ls were isolated from biopsy tissue and analyzed by flow cytometry. Re sults: Ten of the 13 biopsies that contained follicles were H. pylori positive. Follicular CD69 was expressed mainly by CD4 + T cells and th e central core of follicles showed double immunopositivity for the B-c ell marker CD19 and transferrin receptor. Also detected was an increas e in the percentage of epithelial cells from H. pylori-positive sample s expressing HLA-DR and beta 2 microglobulin, compared to negative sam ples (61 +/- 15% vs 9 +/- 9%,p = 0.003 and 93 +/- 7% vs 52 +/- 18%,p = 0.002, respectively), whereas no variation on class I HLA was detecte d. Conclusions: These results suggest that chronic H. pylori infection could facilitate the persistance of follicles on which continuous fol licular helper T-cell activation could lead to uncontrolled follicular B-cell proliferation. Furthermore, beta 2 microglobulin expression by epithelial cells in a nonparallel way to class I HLA may indicate the possibility of nonclassical class I MHC expression on the basal surfa ce of the epithelium. (C) 1998 by Am. Coll. of Gastroenterology.