Alteration in the responsiveness to tumour necrosis factor-alpha is crucial for maximal expression of monocyte chemoattractant protein-1 in human neutrophils

We previously reported delayed expression of monocyte chemoattractant prote in-1 (MCP-1) in human neutrophils cultured with a cytokine-rich crude super natant of phytohaemagglutinin-stimulated peripheral blood mononuclear cells (PHA-sup). Tumour necrosis factor-alpha (TNF-alpha) contained in the PHA-s up played a key role in this event, but there appeared to be another factor (s) in the same supernatant that co-operated with TNF-alpha for maximal MCP -1 expression. In the present study, we reduced TNF-alpha concentrations in the PHA-sup to minimal levels using anti-TNF-alpha affinity columns (TNF-d epleted-sup) and investigated the co-operation between TNF-alpha and TNF-de pleted-sup. Nine hours of preincubation with TNF-depleted-sup altered the r esponsiveness of neutrophils to TNF-alpha and enabled TNF-alpha to increase the level of MCP-1 expression to a maximal level within 4 hr. The priming effect was not due to the increased expression of cell-surface TNF receptor s. However, the activation of primed cells by TNF-alpha was clearly through TNF receptor-p55. Finally, the activity in the TNF-depleted-sup that co-op erated with TNF-alpha was eluted at 60 000 MW on high-performance liquid ch romatography-gel filtration. Thus, delayed neutrophil expression of MCP-1 i s regulated by a cytokine-dependent mechanism that induces neutrophils to e nter a 'mature' stage.