Synergism between interleukin-1? and tumor necrosis factor-? in production by 3T3 cells of a chemotactic factor for rat polymorphonuclear leukocytes

Recombinant human interleukin-1 beta (IL-1) and tumor necrosis factor-alpha (TNF) synergistically stimulated BALB/c 3T3 cells to produce a chemotactic factor for rat polymorphonuclear leukocytes (PMNs), whereas an addition of 10(-11)-10(-8) M IL-1 or TNF alone to the cell culture resulted in a slight increase in the production of chemotactic factor. The partially purified factor was not a chemokinetic but chemotactic factor for PMNs when analyzed by checkerboard analysis. The partially purified factor was trypsin sensitive and heat stable; its isoelectric point was 8.5-10, and its molecular weight was about 10 kDa as estimated by gel filtration. These results suggest that fibroblasts may participate in PMN migration to the inflammatory site where both IL-1 and TNF are released by activated inflammatory cells, including macrophages.