LPS-stimulated expression of a tumor necrosis factor-alpha mRNA in primary trout monocytes and in vitro differentiated macrophages.

We have characterised the lipopolysaccharide (LPS) induction and stability of a tumor necrosis factor-alpha (TNFalpha) mRNA in both monocytes and mature macrophages cultured from trout head kidney. Macrophages differentiated in vitro significantly change in phenotypic appearance, phagocytic capacity and upon LPS exposure display a greatly increased capacity for trout TNFalpha (tTNF-alpha) mRNA expression over that of freshly isolated monocytes. The half-life of the tTNF-alpha mRNA in macrophages is approximately 40 min suggesting that control mechanisms for labile cytokine mRNAs in teleosts may be similar to that found in mammals. Our results suggest that in fish, terminally differentiated macrophages play a central and key role in TNF production as a response to infection. Copyright 2003 Elsevier Science Ltd.