Measurement of human and murine stem cell factor (c-kit ligand)

Stem cell factor (SCF) is an early-acting, hematopoietic growth factor that binds to the receptor encoded by the proto-oncogene c-kit. It is a potent growth factor for primitive bone marrow cells as well as thymocytes. This unit describes three protocols for detecting human and murine SCF. In the first, human or rodent SCF is measured by its ability to stimulate proliferation of the human megakaryoblastic leukemia cell line, UT-7. Because rat and mouse SCF bind well to human c-kit, human and rodent SCF can both be measured using the first basic protocol. In an Alternate Protocol, rodent SCF is assayed by its ability to stimulate proliferation of the clonal murine mast cell line, MC/9. Human SCF is not very active on rodent cells and thus cannot be measured using this protocol. Both of the cell proliferation assays lack specificity because they are capable of detecting other cytokines in addition to SCF. The third protocol is a radioreceptor assay using the human erythroleukemia cell line, OCIM1; it specifically measures murine or human SCF and not other cytokines. Support protocols describe maintenance of UT-7 and MC/9 cells and preparation of plasma membranes from OCIM1 cells.