SECRETION OF BIOACTIVE GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR HUMAN COLORECTAL-CARCINOMA CELLS

Secretion of several cytokines by colorectal carcinoma cells has been substantiated. These do not include granulocyte-macrophage colony-stim ulating factor (GM-CSF) thus far. We show that the supernatant of two human colorectal carcinoma cell lines, LS1034 and SW480, stimulates pr oliferation of GM-CSF-dependent M07e cells. The activity was constitut ively secreted by LS10354 cells and could be induced by serum-free cul ture conditions in SW480 cells. Addition of a neutralizing anti-GM-CSF antibody completely inhibited this activity. Preabsorption with anti- GM-CSF antibody removed all M07e growth-stimulating activity from LS10 34 and SW480 supernatant. Western blot analysis revealed the presence of GM-CSF in LS1034 supernatant. Our results indicate that human color ectal carcinoma cells secrete indeed biologically active GM-CSF.