Oral-mucosal administration of IFN-alpha potentiates immune response in mice.

We studied the effects of oral-mucosal administration of murine interferon-alpha (Mu-IFN-alpha) on immune responses and infection with vaccinia virus (VV) in mice. When Mu-IFN-alpha was administered to sheep red blood cell (SRBC)-sensitized mice for 4 or 5 days, Mu-IFN-alpha significantly enhanced delayed-type hypersensitivity (DTH) and antibody production, with maximum enhancement of each at 1 IU/body. To investigate the antiviral effect of oral-mucosal Mu-IFN-alpha, mice were infected with VV, and Mu-IFN-alpha was administered for 15 days. Pocks were observed in the tail skin of infected mice, and Mu-IFN-alpha at doses of 1, 10, and 100 IU/body significantly suppressed pock formation. Also, VV-specific cytotoxic T cells (CTL) were observed in the spleen from the same mice at 7 days after infection, and Mu-IFN-alpha enhanced CTL activity at doses above 1 IU/body. These results suggest that the oral-mucosal Mu-IFN-alpha may have potentiating effects on cellular and humoral immune responses, which may contribute to its effects against VV.