Potential application of human interferon-alpha in microbial infections of the oral cavity.

We have been evaluating the potential use of interferon-α (IFN-α) against fungal infections of the oral cavity. IFN-α has been reported to enhance the antifungal activity of neutrophils. This cytokine is also known to synergize with interleukin-1 in enhancing a number of inununomodulatory responses. To study cytokine involvement in oral defense mechanisms against microbial infection, we first demonstrated the presence of antimicrobial interleukins (IL)-1α, IL-1β, and IL-8 in the saliva, which can all augment the microbicidal activity of neutrophils, and the presence of epithelial cells and neutrophils in oral lavage fluid from healthy volunteers. Immunostaining for cytokines produced by these cells showed that the candidate producers of both IL-1α and IL-8 are epithelial cells, but those of IL-1β remained inconclusive. We next found that IFN-α enhanced IL-1α-augmented neutrophil-mediated anticandidal action while marginally enhancing IL-8- and IL-1β-mediated reactions. These results suggest that IFN-α is ...