Effects of intranasal immunization on protective immunity against otitis media

It has been reported that intranasal immunization can induce mucosal immune responses. However, the efficacy of intranasal immunization on otitis media caused by non-typeable Haemophilus influenzae (NTHi) is not yet elucidated. Mice were intranasally, orally, intratracheally or intraperitoneally immunized with outer membrane protein (OMP) isolated from NTHi, and antigen-specific immune responses were determined by enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immuno-spot assay (ELISPOT). Cytokine production from splenic CD4+ T cells was examined by ELISA. Following the immunization, the clearance of NTHi from the nasal and nasopharyngeal cavity was examined. OMP-specific IgA antibody titers in nasal washes and the numbers of specific IgA-producing cells in nasal passages were significantly increased in intranasally immunized mice. Cytokine analysis showed that interferon-gamma (IFN-gamma) and interleukins IL-6 and IL-10 were predominantly produced from CD4+ T cells. The clearance of NTHi was significantly enhanced in the intranasal immunization group. Intranasal immunization is an effective vaccination regimen for the induction of OMP-specific mucosal immune responses.