Interferon induced in human leukocytes by concanavalin A: isolation and characterization of gamma- and beta-type...

Interferon (IFN) was induced in suspensions of fresh human leukocytes by incubation with concanavalin A (Con A). The crude supernatant was concentrated and partially purified by adsorption to silicic acid and elution with an ethylene glycol (EG)-containing buffer. Th EG eluate was shown to contain two antivirally active components (tentatively called 22K), separable from each other by gel filtration. The 45K component was strictly species specific, relatively sensitive to acid (pH 2) and poorly neutralized by anti-human IFN-beta (HuIFN-beta) antibody. In all probability, it predominantly contained (a) molecular variant(s) of human gamma-type IFN (HuIFN-gamma ). The 22K component was acid resistant and serologically indistinguishable from HuIFN-beta prepared from fibroblasts. However, in contrast to the latter, it had little activity on bovine kidney cells and no activity on human HEp-2 and monkey Vero cells. A preparation with the same properties was obtained by substituting glycine buffer (pH 2) for EG in the elution of Con A-induced IFN from silicic acid. This IFN failed to adsorb to a zinc chelate column, while HuIFN-beta from fibroblasts can easily be purified by affinity chromatography on this type of column. It was concluded that the Con A-induced IFN contained an acid-resistant component of apparent molecular weight 22000 serologically related to classical HuIFN-beta but differing by certain physicochemical and biological criteria.