γ-Interferon (IFN-γ) was shown to amplify cytotoxin release from murine bone marrow-adherent macrophages in response to an animal lectin as a second stimulus. This stimulation of cytotoxin release was demonstrated both in vitro and in vivo and was maximal 2 h after treatment with IFN-γ. No change in expression of surface antigens was detected on bone marrow-adherent cells treated with IFN-γ. IFN-γ also augmented production of cytotoxin from bone marrow-adherent cells that had been cultured for several days. This cytotoxin was inhibited by rabbit anti-tumor necrosis factor serum and had a molecular weight of 70,000. These findings showed that both freshly isolated and cultured bone marrow macrophages could release cytotoxin and that cytotoxin production in response to a second stimulus was augmented by IFN-γ. The results also suggest that IFN-γ can activate all macrophages in vivo, irrespective of their states of maturation and differentiation.

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©1988 American Association for Cancer Research.
1988
American Association for Cancer Research, Inc.