REGULATION OF TNF-ALPHA AND IL-1 GENE-EXPRESSION DURING TPA-INDUCED DIFFERENTIATION OF MALIGNANT HISTIOCYTOSIS DEL CELL-LINE T(5-6) (Q35-P21)

The production of TNF-alpha and IL-1 alpha and beta molecules has been shown to be associated with the proliferation and activation of cells of the monocyte/macrophage series the intermediate steps in the synth esis of these molecules have been less investigated Unstimulated and T PA stimulated DEL cells (a CD30-positive, t(5;6)(q35;p21) malignant hi stiocytosis cell line) were used to study the expression of TNF-alpha and IL-1 genes and to evaluate, by nuclear run-on assay and biological measurements, the control of their transcription and the level of pro tein production. To refine this analysis, the effects of cycloheximide and actinomycin D were also evaluated in this investigation. Followin g TPA stimulation, transcription of TNF-alpha (constitutively present) increased threefold as early as 30 mins and stat-red decreasing by 24 h. Cycloheximide superinduced the expression of TNF-alpha mRNA and ac cordingly, the release of its protein. By contrast, transcription of I L-1 molecules appeared de novo and did not result in a biologically de tectable protein. Measurements of RNA half life after actinomycin D in dicated that TNF-alpha and IL-1 alpha mRNAs are not as stable as that of IL-1 beta. These results indicate that, despite their common synerg istic activity, the transcriptional and post-transcriptional mechanism s regulating the synthesis of TNF-alpha and IL-1 alpha and IL-1 beta i nvolve different pathways.