Protective effect of mucosal administration of recombinant human macrophage colony-stimulating factor (rhM-CSF) on mucosal infection of Sendai virus in mice.

We investigated the protection confered by the mucosal administration of recombinant human macrophage colony-stimulating factor (rhM-CSF) against mucosal infection of Sendai virus in mice. In an experimental infection model using Sendai virus, an intranasal (i.n.) administration of rhM-CSF (20 micrograms per mouse) 2 days before injection induced significant protection against a lethal infection of this virus. Also, its antiviral activity was dependent upon the dose of rhM-CSF. However, a subcutaneous (s.c.) administration of rhM-CSF with an effective dose (20 micrograms per mouse) i.n. did not confer protection. In a time course analysis of virus growth in the lungs, mice given rhM-CSF. i.n. significantly inhibited the early period of infection, compared with the untreated mice. Moreover, the level of interferon-gamma (IFN-gamma) in lung wash fluids from the rhM-CSF-treated mice was higher than that of the untreated mice. These results suggested that the mucosal (i.n.), but not the systemic (s.c.) administration of rhM-CSF augments host resistance against mucosal infection with Sendai virus, and that its prophylactic activity is related to growth inhibition of the virus and enhanced IFN-gamma secretion in the lungs.