Antibody to purified human colony-stimulating factor: use in the identification and isolation of granulocyte macrophage progenitor cells.

Conditioned media prepared from human lung, placenta, peripheral leukocytes, cultured human pancreatic carcinoma cells, and cultured cervical carcinoma cells exhibit a common pattern of two distinct types of colony-stimulating factors (CSF) separable by isoelectrofocusing. Type I and type II CSF differ in MW, isoelectric point, CFU-C specificity, and the morphologic type of colonies they stimulate. Type I CSF exhibits higher activity in mouse than in human marrow while type II is more active in human marrow. Type I and II CSF from cultured human pancreatic carcinoma have been purified, type I to apparent homogeneity, and antibody has been prepared against them in rabbits. We have utilized purified CSF and anti-CSF antibodies to label CFU-C fluorescently for the purpose of cell sorting via flow photometry. Human bone marrow cells preincubated with CSF and then treated first with anti-CSF antibody then fluorescein-labeled goat antirabbit globulin retain their ability to grow and form aggregates in the presence of additional CSF. Colonies thus formed exhibit fluorescence, the intensity of which diminishes with increase in aggregate size. These observations provide new insight into the biology of CFU-C and suggest the following: (1) Incubation of marrow cells with CSF for 2 h results in binding of CSF or an antigenic component of CSF to membranes of CFU-C. (2) Bound CSF-anti CSF complex remains on CFU-C membranes through at least 5-6 cell divisions. (3) The approach described offers great potential for the preparation of highly purified CFU-C populations by fluorescence cell sorting.