Fucose-activated killer cells. I. Enhanced TNF-alpha mRNA accumulation and protein production.
Our previous studies have shown that the monosaccharide alpha-L-fucose significantly enhances the cytolytic capacity of peripheral blood mononuclear leukocytes (PBMLs). To examine possible mechanisms through which fucose affects cytolytic activity, we studied the production of cytokines after alpha-L-fucose stimulation. In this report, we show that fucose induced a minor but significant augmentation of production of interleukin-2 (IL-2), but anti-IL-2 antibodies did not completely inhibit fucose-activated cytolysis. Fucose induced significantly higher secretion of TNF-alpha by both lymphocytes and monocytes. The nature of the lytic molecule detected in the TNF bioassay was verified with specific neutralizing antibodies. In addition, fucose induced the accumulation of TNF-alpha mRNA in a time-dependent manner with a peak at 8 h and a return to baseline values at 20 h after stimulation. In vitro nuclear transcription assays determined that fucose augmented the rate of transcription of the TNF-alpha gene, and inhibition of de novo transcription with actinomycin D indicated that the turnover rate of the TNF-alpha mRNA was not affected by fucose stimulation. We also determined that fucose did not modulate the mRNA expression of the pore-forming protein, a major lytic protein involved in lymphocyte cytotoxicity. Specific neutralizing antibodies indicated that TNF-alpha was not an effector molecule in fucose-activated killing of K562 or Raji target cells but that this cytokine had an essential role in the induction of the augmented killing by alpha-L-fucose.
Stanková
J
J
Immunology Division, Faculty of Medicine, University of Sherbrooke, Québec, Canada.
D003602:Cytotoxicity, Immunologic; D005643:Fucose / Q000494:pharmacology*; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics*
D007376:Interleukin-2; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D005643:Fucose