The identification and partial characterization of a human mononuclear cell-derived neutrophil chemotactic factor apparently distinct from IL-1, IL-2, GM-CSF, TNF and IFN-gamma.

We have identified a neutrophil chemotactic factor (NCF) in supernatants from human blood mononuclear cells (MNC) cultured in the presence of phytohaemagglutinin (PHA). Maximal activity was observed 48 hr after culture. Following gel filtration, NCF eluted as a single major peak, together with proteins, having a molecular size of approximately 10,000 MW. The material gave a single band on SDS-PAGE but was heterogeneous following chromatofocusing (pIs approximately 6.8-7.0, 5.5-6.0 and 5.0). The biological activity of the partially purified material was abolished by trypsin and chymotrypsin treatment. NCF was heat stable (70 degrees, 60 min) and promoted both directional migration (chemotaxis) of neutrophils and, to a lesser extent, stimulated random locomotion (chemokinesis). The factor was not associated with detectable amounts of IL-1, IL-2 or interferon-gamma (IFN-gamma). MNC-derived NCF had a molecular size lower than recombinant granulocyte-monocyte colony-stimulating factor (rGM-CSF) and recombinant tumour necrosis factor (rTNF), and was considerably more active in chemotaxis. Optimal chemotactic concentrations of partially purified MNC-derived NCF were of comparable potency to FMLP and LTB4 and had about 60% of the activity of optimal concentrations of C5a, C5a-des-Arg and platelet-activating factor (PAF). These experiments indicate that the human MNC-derived NCF is a potent chemo-attractant distinct from other cytokines previously reported to promote neutrophil locomotion.