THE PHYSIOLOGICAL INTERFERON RESPONSE .2. INTERFERON IS PRESENT IN LYMPH BUT NOT IN PLASMA OF HEALTHY RABBITS

If interferon is produced by the gut-associated lymphoid tissue of healthy rabbits under normal conditions and is not all bound in situ, it may spill over and be detectable in lymph. Antiviral activity was measured in lymph and plasma simultaneously. Antiviral activity was consistently measurable in abdominal and thoracic lymph but not in plasma or in the lymph collected from the hind leg duct. The antiviral activity was neither due to lipoproteins, nor Ig, nor to cell-produced viral inhibitors other than interferons. Extensive characterization of the antiviral activity indicated that the inhibitor is either rabbit interferon-.gamma. or an acid-labile inteferon-.alpha. or a mixture; appropriate antisera will be necesssary to resolve this uncertainty. The results support the view of the existence of a physiological interferon response.