INHIBITION BY INTERLEUKIN-4 OF CONSTITUTIVE BETA-INTERFERON SYNTHESISIN MOUSE MACROPHAGES

We have found that interleukin-4 (IL-4) abrogated constitutive beta in terferon (IFN-beta) synthesis in mouse macrophages. Analysis of endoge nous IFN mRNA by reverse transcription-PCR clearly documented the pres ence of IFN-beta but not of IFN-alpha transcripts in RNA from bone mar row-derived macrophages (BMM). Culture of bone marrow cells for 7 days in the presence of macrophage colony-stimulating factor plus IL-4 or treatment of mature BMM with IL-4 for 3 to 4 days resulted in pronounc ed inhibition of IFN-beta transcript levels, As a consequence, BMM bec ame highly permissive to viral infection and induction of the IFN-resp onsive 2',5'-oligoadenylate synthetase was inhibited. In view of the e vidence for low-level constitutive secretion of IFN in vivo, it is pos sible that IL-4 influences the host's antiviral defense system.