Human monocyte-derived chemotactic factor for granulocytes.

Production of the chemotactic factor for granulocytes (CFG) by human mononuclear cells was studied using the agarose plate method. CFG was produced by mononuclear cells placed in an agarose well, and a chemotactic gradient was formed in the surrounding area. The degree of CFG production by mononuclear cells was estimated by the chemotactic response of indicator granulocytes which were placed in separated agarose wells in the same dish. CFG production was observed after 3 h culture in a well where LPS or anti-beta 2 microglobulin serum stimulated mononuclear cells were placed. CFG did not show chemotactic activity for monocytes. PHA, Con A, PWM and Sepharose-Protein A failed to activate mononuclear cells to produce significant amounts of CFG compared with non-stimulated cells. There was a dose-response relationship between the chemotactic activity of the CFG produced and the number of phagocytic mononuclear cells in well culture. Thus it was concluded that the CFG-producing cells are not lymphocytes, but phagocytic mononuclear cells or monocytes.