Differential effects of recombinant human interferon-alpha A/D on expression of three types of Fc receptors on murine macrophages in vivo and in vitro.

Recombinant human interferon-alpha A/D (IFN-alpha A/D) is known to act on murine cells. We studied the in vivo and in vitro effects of pure IFN-alpha A/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-alpha A/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-alpha A/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-alpha A/D. On the other hand, IFN-alpha A/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-alpha A/D also increased the FcRI expression. In contrast with in vivo treatment, however, IFN-alpha A/D treatment in vitro did not bring about any change in the FcRII expression. The FcRIII expression also remained unchanged with IFN-alpha A/D in vitro. Lymphokine-rich mouse spleen cell supernatants which contained natural IFN-gamma again enhanced the FcRI expression, but did not modulate the expressions of FcRII or FcRIII in vitro.