The effect of Helicobacter hepaticus infection on immune responses specific to herpes simplex virus type 1 and characteristics of dendritic cells.

Infection of mice with Helicobacter hepaticus is common in research colonies, yet little is known about how this persistent infection affects immunologic research. The goal of this study was to determine whether H. hepaticus infection status can modulate immune responses specific to herpes simplex virus type 1 (HSV1) and the phenotypic and functional characteristics of dendritic cells (DC) of mice. We compared virus-specific antibody and T cell-mediated responses in H. hepaticus-infected and noninfected mice that were inoculated intranasally with HSV1. The effect of H. hepaticus on the HSV1-specific antibody and T cell-mediated immune responses in superficial cervical and tracheobronchal lymph nodes (LN) did not reach statistical significance. Surface expression of the maturation-associated markers CD40, CD80, CD86, and MHC II and percentages of IL12p40- and TNFalpha-producing DC from spleen and colic LN in H. hepaticus-infected mice and noninfected mice were measured in separate experiments. Expression of CD40, CD86, and MHC II and percentages of IL12p40- and TNFalpha-producing DC from colic LN were decreased in H. hepaticus-infected mice. In contrast, H. hepaticus infection did not reduce the expression of these molecules by splenic DC. Expression of CD40, CD80, CD86, and MHC II on splenic DC from H. hepaticus-infected mice was increased after in vitro lipopolysaccharide stimulation. These results indicate that H. hepaticus infection can influence the results of immunologic assays in mice and support the use of H. hepaticus-free mice in immunologic research.