Different proteins are induced by alpha- and gamma-interferon in hairy cell leukemia

Despite the striking antiproliferative effect of alpha-interferon (alpha-IFN) in hairy cell leukemia, gamma-interferon (gamma-IFN) does not appear to have such an effect. We have previously demonstrated the induction of synthesis of specific proteins by alpha-IFN, both in vitro and in vivo. We have now shown that gamma-IFN induces synthesis of specific proteins, but the pattern differs from that seen after alpha-IFN exposure. The prominent 80,000-dalton protein induced by alpha-IFN was not induced by gamma-IFN, and the prominent 62,000-dalton protein induced by gamma-IFN was only rarely induced by alpha-IFN. Two other proteins were induced by both alpha-IFN and gamma-IFN. The other proteins induced by alpha-IFN were not induced by gamma-IFN. These differences may be related to the different biological response of hairy cells to the two types of IFN. We also showed for both alpha-IFN and gamma-IFN that some IFN-induced proteins are probably transported to the nucleus of the hairy cell, although the majority of proteins induced by both alpha-IFN and gamma-IFN were in the cytosol/membrane fraction of the cell. We have therefore demonstrated that gamma-IFN does have a biochemical effect on hairy cells in terms of induction of specific protein synthesis, leading to the inference that hairy cells must possess another receptor at least functionally analogous to the type II IFN receptors on fibroblasts, with which gamma-IFN interacts.