CHLOROQUINE INHIBITS MACROPHAGE TUMOR-NECROSIS-FACTOR-ALPHA MESSENGER-RNA TRANSCRIPTION

Although chloroquine administration in vivo following haemorrhage in mice decreases tumour necrosis factor-alpha (TNF-alpha) release by macrophage (Mphi), the mechanism remains unknown. To study this, peritoneal Mphi (pMphi) from unmanipulated, sham-operated and post-haemorrhage mice were isolated, treated with 0.13 mg/ml chloroquine for 2 hr, and then stimulated with lipopolysaccharide (LPS) for 48 hr. Pretreatment of pMphi from various groups of mice with chloroquine resulted in 75-90% inhibition of TNF-alpha release, determined by bioassay. Total RNA was isolated from pMphi and murine Mphi-derived cell lines (P388D1 and RAW 264.7), stimulated with LPS for 0.5 or 1 hr, respectively, and Northern blot analysis for TNF-alpha mRNA performed. Chloroquine inhibited TNF-alpha mRNA expression without interfering with mRNA stability, suggesting that this agent reduces Mphi TNF-alpha release by disrupting TNF-alpha gene transcription.