Absence of biological effects of orally administered interferon-beta ser

To assess biological effectiveness of interferon (IFN) administered orally, we measured serum IFN and several proteins and metabolites induced by IFN after oral administration of 2.5 mg or 7.5 mg of recombinant IFN-beta ser to 6 healthy volunteers. These IFN-induced metabolites, beta 2-microglobulin, and neopterin in serum, and 2',5'-oligoadenylate (2-5A) synthetase in peripheral blood mononuclear cells, are more sensitive to the presence of IFN than bioassay of IFN in serum. Up to 48 h after oral IFN was administered, serum IFN, beta 2-microglobulin, neopterin, or 2-5A synthetase were not generally increased compared to pretreatment levels, indicating that oral IFN had no significant biological effects.