Comparison of patterns of expression of tumour necrosis factor, lymphotoxin and interleukin-6 mRNA.

The expression of the mRNA encoding tumour necrosis factor, lymphotoxin and interleukin-6 by peripheral blood mononuclear cells was analysed. Unstimulated cells contained no detectable mRNA for these cytokines, however each mRNA was transiently expressed after stimulation with either the combination of phytohaemagglutinin and phorbol ester or the single stimulus of lipopolysaccharide. The dual stimulus yielded the stronger signal. The cytokine mRNA's had short half lives, but were stabilised following protein synthesis inhibition. Cyclosporin A completely blocked induction of lymphotoxin and partially inhibited induction of TNF and IL-6 mRNA. The features of regulation described in this paper suggest these genes belong within the "early" set of genes expressed following immune cell activation.