EFFECT OF ORAL IMMUNIZATION WITH RECOMBINANT UREASE ON MURINE HELICOBACTER-FELIS GASTRITIS

The ability of oral immunization to interfere with the establishment o f infection with Helicobacter felis was examined, Groups of Swiss Webs ter mice were immunized orally with 250 mu g of Helicobacter pylori re combinant urease (rUrease) and 10 mu g of cholera toxin (CT) adjuvant, 1 mg of H. felis sonicate antigens and CT, or phosphate-buffered sali ne (PBS) and CT. Oral immunization with rUrease resulted in markedly e levated serum immunoglobulin G (IgG), serum IgA, and intestinal IgA an tibody responses. Challenge with live H. felis further stimulated the urease-specific intestinal IgA and serum IgG and IgA antibody levels i n mice previously immunized with rUrease but activated primarily the s erum IgG compartment of PBS-treated and H. felis-immunized mice, Intes tinal IgA and serum IgG and IgA anti-urease antibody responses were hi ghest in rUrease-immunized mice at the termination of the experiment, Mice immunized with rUrease were significantly protected (P less than or equal to 0.0476) against infection when challenged with H. felis 2 or 6 weeks post-oral immunization in comparison with PBS-treated mice, Whereas H. felis-infected mice displayed multifocal gastric mucosal l ymphoid follicles consisting of CD45R(+) B cells surrounded by cluster s of Thy1.2(+) T cells, gastric tissue from rUrease-immunized mice con tained few CD45R(+) B cells and infrequent mucosal follicles, These ob servations show that oral immunization with rUrease confers protection against H. felis infection and suggest that gastric tissue may functi on as an effector organ of the mucosal immune system which reflects th e extent of local antigenic stimulation,