Inactivators of fibroblast interferon found in human serum

Investigation of the inactivators of fibroblast interferon has shown that those substances could be identified in every specimen of serum taken from normal individuals. These inactivators were found to destroy a mean of 82% of the interferon antiviral activity beyond that caused by the effects of temperature alone. The inactivators exerted no effect at 4 degrees C but were found in a variety of animal as well as human sera. Although slight differences were found to exist in the extent of inactivation when comparing normal human serum to serum from patients (i) receiving chronic hemodialysis, (ii) with jaundice, or (iii) with underlying malignancies, the differences did not appear to be clinically significant. In exploring the nature of the substances, we found that both dialyzable and non-dialyzable inactivators exist, but the former appear to be the major factors responsible for the unwanted process.