PREPARATION OF A MONOCLONAL-ANTIBODY DIRECTED AGAINST THE RECEPTOR FOR MURINE COLONY-STIMULATING FACTOR-I

Studies were undertaken to produce monoclonal antibodies directed agai nst the murine receptor for macrophage colony-stimulating factor (M-CS F or CSF-I). Sprague-Dawley rats were injected with lysates prepared f rom a murine myelomonocytic cell line (RAW cell line) that has high le vels of M-CSF receptors. Spleen cells from immunized animals were fuse d with murine plasmacytoma cells and expanded. Supernatants from these cells caused inhibition of I-125-CSF binding to either RAW cells or n ormal murine marrow cells. Antibody-producing cells were cloned by lim iting dilution and by colony growth in agar. The antireceptor antibodi es appear specific as they neutralize colony formation by M-CSF but ha ve little or no effect on colony growth in response to the other hemop oietic growth factors granulocyte CSF (G-CSF), granulocytemacrophage C SF (GM-CSF), interleukin-3 (IL-3) or erythropoietin. These antibodies should aid in defining the role of M-CSF in hemopoiesis in vivo.