Comparison of different routes of vaccination for eliciting antibody responses in the human stomach.

Determination of optimal routes to induce mucosal immune responses locally in the stomach and duodenum are important steps in the development of vaccines against Helicobacter pylori infection. In this study, we immunized H. pylori-infected individuals either nasally or rectally with a model antigen, i.e. cholera toxin B subunit, and compared the immune responses after these routes with the responses after oral or intrajejunal vaccination. Specific antibody levels in serum as well as specific antibody levels and antibody-secreting cells in biopsies from antrum and duodenum were determined by ELISA and ELISPOT methods. In contrast to oral vaccination, nasal and rectal vaccination did not induce significant increases in specific antibody-secreting cells either in the antrum or duodenum. Furthermore, when analyzing the antibody levels in saponin extracted biopsies, intrajejunal vaccination was superior to both nasal and rectal vaccination in inducing antigen-specific IgA levels in the stomach. We conclude that oral vaccination is the optimal route for induction of antigen-specific IgA antibody responses in the stomach and duodenum of humans, while nasal or rectal vaccination is less suitable for this purpose.