[Cryomethod of concentrating interferon (author's transl)]

The fact of non-simultaneous thawing of protein and water was used for concentration of interferon from pre-frozen preparations. As thawing proceeded, 5 sequential fractions equal in a volume were removed from preparations of human leucocyte, mouse macrophage and tissue chick interferons; the titers of their antiveral activity in the first fraction were 4--8-fold higher than the initial titer, and this activity decreased gradually to a titer which was 2-fold lower than the initial in the fifth fraction. The total amount of interferon units in all the fractions was 1.8--3.8-fold higher than in the initial preparation taken in a volume corresponding to the total volume of all the fractions. As addition of the Vth fraction to the Ist fraction reduced the titer of interferon in it to the initial level, it is suggested that in interferon preparations there is an inhibitor of its effect, "anti-interferon".