IMMUNIZATION OF BALB C MICE WITH HELICOBACTER UREASE-B INDUCES A T-HELPER-2 RESPONSE ABSENT IN HELICOBACTER INFECTION/

Background & Aims: Infection with Helicobacter induces a T helper type 1 response in mice and humans, Mice can be cured or protected from in fection with Helicobacter by mucosal immunization with recombinant H. pylori urease B subunit (rUreB), This study characterizes the immune r esponse of infected mice immunized with rUreB, Methods: BALB/c mice we re infected with H, felis. Two weeks later, they were orally immunized four times with rUreB and cholera toxin (CT) at weekly intervals. Con trols were only infected or sham-immunized with CT. Animals were kille d at various times after immunization, Splenic CD4(+) cells were obtai ned and cultured in vitro with rUreB to evaluate antigen-specific prol iferation and induction of interferon gamma and interleukin 4 secretio n. Results: All rUreB-immunized mice (n = 8) were cured from infection 3 weeks after the fourth immunization. Immunization induced a prolife rative response of splenic CD4(+) cells, a progressive decrease in int erferon gamma secretion, and a concomitant increase in interleukin 4 s ecretion after each immunization. A simultaneous increase in rUreB spe cific serum immunoglobulin G1 levels was observed in infected/immunize d mice. Conclusions: In BALB/c mice, therapeutic mucosal immunization with rUreB induces progressively a Th2 CD4(+) T cell response resultin g in the elimination of the pathogen,