Modulation of the immune response by the use of
biological response modifiers (BRM) is aimed at amplifying the host resistance against
cancer. Studies on inhibition of
tumor growth on an in vitro model, in which human
breast carcinoma (HBL-100) and human lung
carcinoma (H125) cells were used as target
tumor cells, confirmed that
interferons (IFNs) alpha and beta can amplify the
antineoplastic effects of immunochemotherapy by enhancing the cytotoxic activity of effector cells and by antagonizing the immunodepressive effects of radiation or anticancer drugs. Moreover, data obtained from a pilot clinical trial, designed to test the effect of low concentrations of beta-IFN on natural cell-mediated cytotoxicity, pointed out a good correlation between the in vitro and in vivo responsiveness to beta-IFN in
cancer patients. The immunomodulating and antiproliferative effects of BRM were also evaluated in a model of viral leukemogenesis in vitro, after
infection of cord blood derived mononuclear cells (CB-MNC) with the human leukemic retrovirus HTLV-I. Alpha-and beta-IFN were previously shown to regulate differentially the
antiviral competence of recipient CB-MNC, by interfering with viral replication and delaying the emergence of the transformed clone(s). One of the mechanisms of IFN action that contributes to control
HTLV-I infection in vitro can be ascribed to their property of partially counteracting the depression of cell-mediated cytotoxicity that follows exposure to HTLV-I. In the light of data previously and herein described, it seems that alpha- and beta-IFN can be considered potential candidates to define combined
therapy with
antiviral drugs, to control the early stages of retrovirus-associated disease in human pathology.