Protection against experimental Helicobacter pylori infection after immunization with inactivated H. pylori whole-cell vaccines.

The protective effect of therapeutic oral immunization with homologous and heterologous formalin-inactivated Helicobacter pylori cells given together with cholera toxin as an adjuvant was evaluated with C57BL/6 mice infected with H. pylori Sydney strain 1 (SS1). The bacteria used for immunization were strains that were either homologous or heterologous with regard to the O antigen (i.e., the Lewis antigen [Le antigen]) expressed by the lipopolysaccharide of the infecting H. pylori SS1 strain. We found that repeated oral immunization with inactivated H. pylori SS1 cells can significantly inhibit an existing infection (P < 0.001) and that the protection induced by such therapeutic immunization extends to protection against reinfection (P < 0.001). A similar level of protection was also achieved by immunization with another inactivated H. pylori strain having the same O antigen (Le antigen) as the infecting H. pylori SS1 strain. In contrast, immunization with inactivated strains expressing a heterologous O antigen, Le(x), provided less protection or no protection. Immunization with H. pylori lysate preparations, on the other hand, resulted in significant comparable protection whether the lysates were prepared from an Le(x) strain or an Le(y) strain. Postimmunization gastritis was seen in mice that were protected after vaccination but not in unimmunized or unprotected mice. In conclusion, therapeutic immunization with inactivated H. pylori whole-cell vaccines may provide strong protection both against experimental H. pylori infection and against later reinfection.

Anatomic segmentation of the intestinal immune response in nonhuman primates: differential distribution of B cells after oral and rectal immunizations to sites defined by their source of vascularization.

We show that the distribution of specific antibodies and antibody-secreting cells in the intestine after oral and rectal immunizations corresponds to the vascularization and lymph drainage patterns of the gut. Oral immunizations induce antibody responses along the parts of the intestine connected to the superior mesenteric vessels and lymph ducts, whereas rectal immunizations induce antibody responses along the parts of the intestine associated with the inferior mesenteric vessels and ducts.

"PERFEXT": a direct method for quantitative assessment of cytokine production in vivo at the local level.

A method termed "PERFEXT", based on sequential perfusion and detergent extraction of lymphoid and non-lymphoid organs, has been developed for the quantitative measurement of cytokines produced at a local level in a given tissue. In vivo treatment of mice with Staphylococcus enterotoxin B (SEB) or lipopolysaccharide (LPS) served as the model systems. Interleukin-2 (IL2) and interferon-gamma (IFN gamma) levels were monitored by ELISA analysis of extracted samples. After local footpad (FP) injection with SEB, spleen and serum IL2 levels peaked at 2-4 h, while IL2 levels peaked at around 4-8 h in both FP and popliteal lymph nodes. SEB injection resulted in increased IFN gamma levels both in the FP and the draining lymph node. The detection of cytokines in the intestine allows for the application of the method at mucosal sites as well, provided enzyme inhibitors are present during the extraction procedure. After FP injection with LPS, IFN gamma production was significantly increased in the draining lymph node and was detectable in the FP, whereas IL2 was undetectable in any organ examined. IL2 and IFN gamma could also be detected at the site of elicitation of a delayed-type hypersensitivity reaction following local FP challenge. Local cytokine production correlated with the swelling response, whereas cytokine production in the spleen did not. IL2 peaked early, followed by a late increase in IFN gamma production, corresponding to the maximum swelling. This simple method should prove useful for analysing the production of other cytokines in vivo in distinct anatomical compartments.