Characteristics of in vitro antiproliferation activity of human interferon-beta

We compared the in vitro antiproliferative activity of highly purified interferon (IFN)-beta (greater than 10(7) U protein/mg in antiviral activity) with that of IFNs-alpha and lymphoblastoid, using human cells of malignant and non-malignant origin. IFN-beta was the least active of three IFNs in suppressing Daudi cell proliferation. Three hematological cells other than Daudi cells cultivated in suspension were insensitive to each of three IFNs. IFN-beta was more active than IFNs-alpha and lymphoblastoid in suppressing all eight epithelioid cells tested and, particularly with respect to five epithelioid cells sensitive to IFN, IFN-beta was seven to 49 times as active as IFN-alpha. These results indicate that suppression of cell proliferation by IFN depends not only on the target cell species but also on the IFN species, and emphasize the need for careful selection of the most appropriate IFN species in therapy. We found that the antiproliferative characteristics of the present IFN-beta preparation were consistent with those reported previously, supporting the idea that IFN-beta molecules in the present preparation were responsible for suppressing cell proliferation. The antiproliferation activity of our preparation was species-specific but not selective for cells of malignant origin; it was absorbable by IFN-sensitive but not by IFN-insensitive cells; and it was achieved by a cytostatic effect.