FIG. 2.

Histopathologic changes in lungs of mice intranasally immunized with influenza virus vaccine plus the mucosal adjuvant CT. Mice (n = 4) were intranasally immunized with influenza virus vaccine (7.5 μg) either alone (A) or in combination with CT (0.1 μg) (B) on days 0 and 7. Three days later, lungs were collected for histology and sections were stained with hematoxylin-eosin. There were no histologic changes in lungs of any mice given antigen alone. However, there was a massive infiltration of cells around the airways and blood vessels throughout the lungs of all mice immunized with antigen plus CT.