Human recombinant macrophage colony-stimulating factor (M-CSF) increases Cl-esterase inhibitor (Cl-INH) synthesis by human monocytes.

The ability of macrophage colony-stimulating factor (M-CSF) to influence production of complement proteins by cultured human monocytes was studied. Three-day-old cultures of human monocytes were treated with 250-1000 U/ml recombinant human M-CSF (Cetus Corporation, Emeryville, CA). After 3 days the M-CSF containing medium was replaced by the same medium without M-CSF, and the cells were cultured for 3 more days. Samples taken at the removal of M-CSF and 3 days later were tested for the concentration of factor B and Cl-esterase inhibitor (Cl-INH) using ELISA methods, and C2 by using an immunohaemolytic assay. M-CSF induced a marked dose-dependent increase in the synthesis of Cl-INH, but did not significantly change Bf and C2 production. The findings suggest that M-CSF is able to influence selectively the complement protein-producing ability of cultured human monocytes.