Binding of Membrane-Anchored Macrophage Colony-Stimulating Factor (M-CSF) to Its Receptor Mediates Specific Adhesion Between Stromal Cells and M-CSF Receptor-Bearing Hematopoietic Cells

Abstract

AbstractTo explore the biologic significance of the membrane-anchored form of macrophage colony-stimulating factor (M-CSF), we examined whether interaction between membrane-bound M-CSF and its receptor mediates intercellular adhesion as well as cell proliferation and differentiation. Human M-CSF receptors were expressed on a murine in-terleukin-3 (IL-3)-dependent cell line, FDC-P2. by DNA transfection with the c-fms gene (FDC-P2-MCSFR). A human bone marrow-derived stromal cell line, KM 102, was used in the cell adhesion assay. The expression of membrane-bound M-CSF on KM102 cells was demonstrated by flow cytometry and immunoblot analysis. After the incubation of parent and transformed FDC-P2 cells on confluent KM 102 cells, nonadherent cells were removed and the cells attached to KM102 cells were examined microscopi-cally. Almost all parent FDC-P2 cells were nonadherent, whereas a significant number of FDC-P2-MCSFR cells bound to KM102 cells. The addition of anti-M-CSF or anti-M-CSF receptor neutralizing antibodies dose-depen-dently inhibited the binding of [3H]-thymidine-labeled FDC-P2-MCSFR cells to KM 102 cells. An excess amount of M-CSF also inhibited the binding. On the other hand, the addition of antibodies against some representative adhesion molecules (vitronectin receptor, Pgp-1/CD44, and VLA-4) did not inhibit the adhesion between FDC-P2-MCSFR cells and KM102 cells. These results support the idea that membrane-anchored M-CSF and its receptor may function as mediators of cell-cell adhesion.