Factors influencing the production of human immune interferon components.

Human interferon (IFN), induced in leukocyte suspensions by mitogens, contains two antivirally active components (45K and 22K), separable from each other by gel filtration. The 45K component was identified as IFN-gamma; the 22K component is serologically related to IFN-beta, but has different physicochemical and biological properties. Relatively large amounts of 22K were produced in leukocyte suspensions isolated from buffy coats after induction with concanavalin A (ConA); induction of plateletpheresis residues with staphylococcal enterotoxin A (SEA) resulted in the production of almost only IFN-gamma (45K). The addition of foetal calf serum (FCS) to the production medium enhanced the yields of IFN-gamma, while the production of 22K remained unchanged. Incubation of the cell suspension in the absence of mitogen gave only small amounts of IFN, containing mostly 22K. Under various conditions tested, the two components had similar kinetics of production. A significant increase of IFN-gamma production was observed when leukocytes were primed with low concentrations of 22K.