Oral administration of interferon-alpha induces a transient decline in oral mucosal immunoglobulins and an increase in interleukin-5

Although administration of interferon-alpha (IFN-alpha) via the oral-mucosal route has shown efficacy in a variety of human and animal diseases, the mechanism of action of orally administered IFN is not clearly understood. To assess the possibility that IFN-alpha given via a lozenge alters the local mucosal immune system, immunoglobulins (Ig) and cytokines were measured in salivary secretions. Volunteers were given low doses of IFN-alpha and saliva was collected over a 24-h period. IgA and precursor IgM were measured by sandwich enzyme-linked immunosorbent assay (ELISA). Salivary concentrations of interleukin-5 (IL-5), the T helper cytokine primarily responsible for the switch from IgM to IgA, were also determined. After oral administration of IFN-alpha, there was an initial decline in IgM and IgA followed by a return to baseline levels by 8-24 h. This change in Ig concentration was associated with a gradual increase in IL-5, consistent with the return of Ig to baseline as a result of modulation by Ig-mediating cytokines.