Isolation of cDNA for a human granulocyte-macrophage colony-stimulating factor by functional expression in mammalian cells

A cDNA sequence coding for a human granulocyte-macrophage colony-stimulating factor has been isolated from cDNA libraries prepared from mRNA derived from concanavalin A-activated human T-cell clones. The libraries constructed in the pcD vector system were screened by transfecting COS-7 monkey cells with DNA pools to express the products encoded by full-length cDNA inserts. By assaying the cell supernatants, we identified clones encoding a factor that stimulates the formation of granulocyte and macrophage colonies from human progenitor cells. These results demonstrate that identification of full-length cDNAs for many colony-stimulating factors may be achieved entirely on the basis of detecting the functional polypeptide produced in mammalian cells.