Chemokine Receptor 5 Expression in Gastric Mucosa of Helicobacter pylori -Infected and Noninfected Children

Abstract

ABSTRACT Experimental data from human adults or animal models indicate that the Helicobacter pylori -specific immune response is dominated by inflammatory T cells of the Th1 type. To investigate whether a Th1 immune response is established in early H . pylori infection, gastric biopsy samples from 70 children were subjected to immunohistochemical analysis. To this end, T cells, B cells, monocytes, neutrophils, and chemokine receptor 5 (CCR5)-expressing (CCR5 + ) cells, which are associated with Th1 immune responses, were quantified. Children were classified according to H . pylori status and clinical, laboratory, and macroscopic (during endoscopy) findings, without knowledge of histological findings. Group 1 included 31 H . pylori -infected children, group 2 contained 24 children with other conditions possibly affecting the stomach, and group 3 contained 15 children without verifiable pathological findings in the stomach. Lymphoid follicles were present in 90% of biopsy samples from group 1 and 48% of those from group 2 but absent in group 3 biopsy samples. Intraepithelial T cells and CCR5 + cells were regularly detected in all groups without significant differences. B cells, monocytes, and neutrophils were not found. In contrast, the numbers of lamina propria T cells ( P < 0.003) and CCR5 + cells ( P < 0.001) were increased significantly in H . pylori- infected children. B cells (in 13 of 66 children) were detected in children with active ( n = 11) or previously cleared ( n = 2) H . pylori infections but were absent in healthy children. The numbers of monocytes (in 10 of 67 children) did not differ among the groups. Calculations indicated that the majority of gastric T cells express CCR5; this finding is in contrast to the low percentage of CCR5 + T cells in the peripheral circulation. Thus, an increase in the numbers of CCR5 + cells in H . pylori -infected stomach mucosa suggests that this molecule may play an important role in gastric immune responses.