IFNA2 and hairy cell leukemia: The administration of recombinant IFNα was shown to trigger the phagocytosis of tumor cells by macrophages and extended the survival of mice in multiple xenograft tumor models [25], and recombinant IFNα was the first cytokine-based drug approved for clinical use in 1986 for hairy cell leukemia, followed by IFNγ in 1991 for chronic granulomatous disease [26].