Virus-vs endotoxin-induced activation of liver macrophages.

The response of liver macrophages (Kupffer cells) to distinct pathogenic material was investigated by comparing virus- and endotoxin-induced macrophage activation. Endotoxin-induced stimulation and induction with Newcastle disease virus (NDV) or Sendai virus led to the release of the same pattern of prostanoids characterized by a predominant production of prostaglandin E2 (PGE2). With respect to peptide mediators, hepatic macrophages secreted tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 after viral induction and endotoxin treatment, respectively. In response to viruses, however, much more interleukin-6 and TNF-alpha was detected than after endotoxin stimulation. Interferon type I (interferon-alpha/beta), on the other hand, was only detected in the supernatants of macrophages infected with viruses, but not of those exposed to endotoxin. This study also revealed that rat TNF-alpha exists in several soluble species, some of which are glycosylated.