Human monocyte-derived dendritic cells produce bioactive gelatinase B: inhibition by IFN-beta.

We studied the secretion of gelatinase B by dendritic cells (DC) generated by culturing human peripheral blood monocytes in granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). First, we found the intracellular expression of gelatinase B on sections of fixed DC pellets. Zymography analysis of the supernatants of DC cultured for 72 h demonstrated the presence of gelatinase B. To determine if DC produce net enzymatic activity, bioactive gelatinase, a novel sensitive fluorescent-activated substrate conversion (FASC) assay was used to complement the zymography data. Culture media of unstimulated DC demonstrated reproducible net gelatinolytic activity. Tumor necrosis factor-α (TNF-α) IL-1β but not lipopolysaccharide (LPS) stimulation caused a significant increase in gelatinase B production in zymography analysis. Both types of stimulation failed to increase net gelatinase activity in FASC assay. Interestingly, interferon-β (IFN-β) significantly diminished both the total zymolytic...