Distinct molecular species of human interferons: requirements for stabilzation and reactivation of human leukocyte and fibroblast interferons.

Human fibroblast interferon preparations were completely stabilized to 100 degrees C by sodium dodecyl sulphate (SDS) in the presence of mercaptoethanol, but only a minor fraction of their activities were stabilized by SDS without mercaptoethanol. On the contarary, human leukocyte interferon preparations were completely stabilized to 100 degrees C by SDS in the absence of mercaptoethanol, but only a minor fraction of their activities were stabilized by SDS in the presence of mercaptoethanol. Furthermore, human fibroblast interferon preparations whose activities had been destroyed by boiling at 100 degrees C were completely reactivated by SDS under reducing conditions, but only a minor part of their activities were restored by SDS in the absence of reduction. On the contrary, human leukocyte interferon preparations whose activities had been destroyed by boiling at 100 degrees C were completely reactivated by SDS in the absence of reduction, but only a minor part of their activities were restored by SDS under reducing conditions. These data suggest that there are distinct molecular species of human interferons.