B cell responses in gastric antrum and duodenum following oral inactivated Helicobacter pylori whole cell (HWC) vaccine and LT(R192G) in H pylori seronegative individuals.

To investigate whether B cell-specific responses could be elicited in the gastric mucosa of Helicobacter pylori (HP) naive subjects, five volunteers ingested three doses of a HP killed whole cell (HWC) vaccine with 25 microg of recombinant heat-labile toxin (LT(R192G)). Two of three subjects had detectable LT(R192G) and HWC IgA antibody secreting cell (ASC) gastric responses. LT(R192G) and HWC responses in duodenal were 5-14-fold higher than those detected in antral biopsies (P<0.01 and P=0.05, respectively). These results provide the first evidence that specific gastric B cell responses can be induced in HP-non-infected individuals following oral immunization.