Polymorphonuclear leukocyte dysfunction during influenza virus infection in chinchillas.

The increased susceptibility of chinchillas after intranasal inoculation of Streptococcus pneumoniae and influenza A virus to pneumococcal otitis media prompted a study to determine whether infection with influenza virus adversely affects polymorphonuclear leukocyte (PMNL) function and thereby impairs host defense. Thirty-four chinchillas were inoculated intranasally with either influenza A virus or sterile saline. The chemotactic, chemiluminescent, and bactericidal activities of the PMNLs were depressed four to eight days after inoculation of the virus compared with the values obtained before inoculation; these activities remained normal in animals inoculated with sterile saline. The maximum reduction in chemotaxis (37%), peak chemiluminescence (53%), and peak bactericidal activity (26%) of the PMNLs was observed on day 6. Phagocytosis remained normal throughout the period after inoculation. Thus, the susceptibility of chinchillas to pneumococcal disease after inoculation with influenza A virus may be due to the impaired chemotactic and oxidative microbicidal activities of PMNLs.