Heterogeneous macrophage-activating factors from extracellular matrix of human embryo fibroblasts

Previously, the author found a low-molecular-weight stimulating activity for macrophages in the extracellular matrix of a human embryo fibroblast cell strain. It showed stimulatory effects on the attachment ability of macrophages and their production of superoxide anion (-O2) and [3H]UTP incorporation (Zool. Sci. 3, (1986) 621-626). When the author further analyzed this activity, it was found to be associated with two different factors which could be separated by ion exchange chromatography. Their molecular weights were estimated to be about 5 kDa and 10 kDa by gel filtration chromatography; they are designated fibroblast-derived macrophage activating factor I and II (FMAF I and II). They were sensitive to trypsin, but resistant to heat and did not show significant colony stimulating factor and interferon activities. In addition, FMAF II exhibited much higher activity for granulocyte RNA synthesis than FMAF I. The properties of these factors are compared with other factors reported previously and the biological significance of the factors is discussed.