Antibodies against influenza and stimulated macrophages in the lung lavage fluid of mice following oral immunization.

Since oral immunization against influenza might be much more convenient than the aerosol or intranasal route, this study was undertaken to compare various routes of immunization with respect to the antibody response and protection. Mice were either not immunized, immunized intranasally, orally, or rectally. - As compared to the control group, statistically significantly more animals in all of the immunization groups developed antibody in the bronchial washings and showed stimulated alveolar macrophages with the largest percent developing antibody and stimulated cells in the nasally immunized group. However, the difference between the three vaccine groups was not statistically significant. - Following challenge with live virus there was a significant rise in lung lavage cells only in the unimmunized, challenged control group. There was no significant rise in the immunized group. - These results suggest that while the respiratory route of immunization may lead to slightly better local antibody production and protection, the oral route is a promising method, and should be tried in humans.