Studies on the Expression of Spontaneous and Induced Interferons in Mouse Peritoneal Macrophages by Means of Monoclonal Antibodies to Mouse Interferons

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Abstract
Monoclonal antibodies (MAbs) to mouse interferons (MuIFN) have been used to characterize the interferon-like activities spontaneously expressed in mouse peritoneal macrophages freshly explanted from normal pathogen-free mice. Injection of mice with MAbs to MuIFN-.alpha. or -.beta. resulted in a significant increase of vesicular stomatitis virus (VSV) multiplication in peritoneal macrophages. Addition of these MAbs to freshly explanted mouse macrophages accelerated the decay of the antiviral state to VSV during the ''ageing'' in vitro of these macrophage cultures. Furthermore, these MAbs to MulIFN-.alpha. or -.beta. markedly inhibited the transfer of the antiviral state from freshly explanted peritoneal cells or macrophages to syngeneic macrophages ''aged'' in vitro permissive for virus replication. These effects were not observed using a nonneutralizing antibody to MuIFN-.alpha., nor with a MAb to MuIFN-.gamma.. In all experiments sheep polyclonal antibodies to MuIFN-.alpha./.beta. were more effective than the corresponding amount of MAbs to MuIFN-.alpha. or -.beta.. A mixture of both these MAbs was more effective than either alone. Interferons produced after stimulation of peritoneal macrophages with Newcastle disease virus (NDV) and of total peritoneal cells with lipopolysaccharides (LPS) have also been characterized by means of MAbs to IFNs. The results of neutralization studies with these antibodies indicated that MuIFN-.beta. was the major component of peritoneal cell IFN (induced by both NDV and LPS) and MuIFN-.alpha. was a minor component (13 to 17%). These data indicate that both MuIFN-.alpha. and -.beta., but not MuIFN-.gamma., are spontaneously present in/on mouse peritoneal macrophages and are produced after stimulation with NDV or LPS.