Antiviral and antiproliferative activities of recombinant human interferon alpha 2, beta and gamma on HTLV-I and ATL cells in vitro.

ATL (Adult T cell leukemia) causes severe immune deficiency. Furthermore, aggravation of immune deficiency is a major problem in chemotherapy of ATL. In expectation of antiviral, antineoplastic and increasing immunological activity, several clinical trials of Interferons (IFNs) on ATL have been reported. However, as the effects have not been generally established, we investigated the in vitro effects of human recombinant interferon (rIFN) alpha 2, beta and gamma on both the infection of human T-cell lymphotropic virus type I (HTLV-I) to normal peripheral blood lymphocytes (PBL) and the growth of ATL cells. The induction of HTLV-I specific antigens on the surface of normal PBL cultured with HTLV-I in vitro was inhibited by the addition of rIFNs in a dose dependent manner. The rIFNs also had dose dependent suppressive effects on the proliferation of ATL cells and one of the ATL cell lines (MT-2). These suppressive effects of rIFNs were not due to a direct cytocidal activity, because rIFNs did not affect the viability of ATL cells at these concentrations. Such inhibitory concentrations (1 to 1000 U/ml) were within the ranges achievable in the blood of patients after the injection of rIFNs. This investigation suggests that rIFNs is applicable for the therapy of ATL.