Changes in the expression of elastase and cathepsin B with differentiation of U937 promonocytes by GMCSF

The human promonocytic cell line, U937, when treated for up to 72h with 12,O,tetradecanoyl-phorbol-13-acetate or granulocyte-macrophage colony-stimulating factor, exhibited increased phagocytic activity and expression of the marker p150/95. There was an associated increase in the monocyte proteinase cathepsin B and its mRNA but decreased cellular levels of neutrophil elastase and elastase mRNA. Granulocyte-macrophage colony-stimulating factor therefore causes differentiation of U937 cells, with appropriate effects on the synthesis of leukocyte proteinases.