Macrophages secrete a novel heparin-binding protein with inflammatory and neutrophil chemokinetic properties

The authors report the identification and purification of a new inflammatory monokine synthesized by the macrophage tumor cell line RAW 264.7 in response to endotoxin. This monokine, which the authors term "macrophage inflammatory protein" (MIP), is a doublet with an apparent molecular mass of similar to 8,000 daltons on SDS-PAGE but forms aggregates of > 2 x 10 super(6) daltons as assessed by gel filtration. Partial NH sub(2)-terminal amino acid sequence data reveal no significant homology with any previously described protein. Although the monokine is anionic under physiological conditions, it is one of two major macrophage-secreted proteins that bind to heparin at high salt concentrations.