Recombinant human interferon-αA/D (IFN-αA/D) is known to act on murine cells. We studied the in vivo and in vitro effects of pure IFN-αA/D on the surface expressions of the three types of murine macrophage Fc receptors (FcRI, II, III). Peritoneal macrophages obtained from BALB/C mice injected 24 h previously with IFN-αA/D showed increased expressions of FcRI and FcRII, because an enhanced capacity to bind monoclonal IgG2a-or IgG2b-coated sheep red blood cells was revealed. However, an optimal IFN-αA/D dose of a distinct narrow range was required to induce the maximum increase in each type of FcR. Furthermore, the antibody-dependent cellular cytotoxicity mediated by either FcRI or FcRII was also increased with the same optimal dose of IFN-αA/D. On the other hand, IFN-αA/D did not induce any change in the surface expression of FcRIII, which was demonstrated by the binding of monoclonal IgG3-coated sheep red blood cells. The in vitro treatment of peritoneal macrophages with IFN-αA/D also increased the FcRI expression. In contrast with in vivo treatment, however, IFN-αA/D treatment in vitro did not bring about any change in the FcRII expression. The FcRIII expression also remained unchanged with IFN-αA/D in vitro. Lymphokine-rich mouse spleen cell supernatants which contained natural IFN-γ again enhanced the FcRI expression, but did not modulate the expressions of FcRII or FcRIII in vitro.
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