Fundus lesions after carotid injection of Streptococcus mutans in monkeys.

Beige mice, which are a homolog of the Chediak-Higashi syndrome, and mice treated with 89Sr to destroy the bone marrow provide animal models of defects in mononuclear phagocyte and natural killer cell functions. The innate resistance of these mice to viruses such as herpes simplex and encephalomyocarditis viruses, however, is normal. Moreover, treatment of the mice with immunomodulators such as Propionibacterium acnes (formerly designated Corynebacterium parvum) and pyran produced a significant increase in resistance to encephalomyocarditis virus. The antiviral effect of P. acnes in 89Sr-treated mice was exhibited during marked monocytopenia and without evidence for an inflammatory influx of macrophages into the peritoneal cavity. Treatment with P. acnes was also effective in increasing the resistance of beige mice to infection with Listeria monocytogenes. Thus, immunomodulators can be effective in mice that exhibit impaired macrophage and natural killer cell functions.