International journal of cancer. Journal international du cancer
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The role of recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) in monocyte-mediated up-regulation of lymphokine-activated killer (LAK) cell induction by IL-2 was examined. Treatment of blood mononuclear cells (MNC) of healthy donors with GM-CSF for 4 days in the presence of IL-2 resulted in a significant increase in LAK activity against natural killer (NK)-resistant Daudi cells, as assessed by the 4 hr 51Cr-release assay. For determination of the role of GM-CSF in LAK induction, highly purified lymphocytes (greater than 99%) and monocytes (greater than 90%) were isolated from MNC by counter-flow centrifugal elutriation (CCE). ⋯ Treatment with anti-GM-CSF antibody completely abolished up-regulation of LAK induction by GM-CSF-treated monocytes. When blood monocytes were separated into 5 fractions by CCE, GM-CSF-responding monocytes were found to be responsible for up-regulation of LAK induction. These results suggest that GM-CSF may be important in monocyte-mediated up-regulation of LAK cell induction in vivo.