Correlation of the Antiproliferative Effect and the Mx-Homologous Protein Induction by IFN in Patients with Malignant Melanoma

The human interferon-induced intracellular protein homologous to the murine Mx-protein has recently been identified by means of a specific monoclonal antibody. Three of six melanoma cell lines elicited this intracellular human Mx-homolog upon incubation with IFN-α or IFN-γ, yet all six melanoma cell lines tested were susceptible to the antiproliferative effect of IFN-α and IFN-α. Compared per antiviral unit, IFN-γ had weaker Mx-inducing but stronger antiproliferative activity than IFN-α. These data suggest that the IFN-induced Mx-homologous protein is not involved in the antiproliferative action of IFN on malignant melanoma cell lines. Furthermore, 51 patients with advanced malignant melanoma were treated thrice weekly with 10 × 106 IU rIFN-α-2b and 6 × 106 nIFN-