Functional changes in THP-1 human monocytic cells after stimulation with lipopolysaccharide of oral microorganisms...

A human THP-1 monocyte cell line culture system has been utilized to observe the effect of granulocyte macrophage colony stimulating factor (GM-CSF) supplementation with lipopolysaccharide (LPS) of oral microorganisms to stimulate monocyte/macrophage functional activity. LPS of oral microorganisms, Fusobacterium nucleatum and Porphyromonas gingivalis was produced by phenol-water extraction and characterized. The phagocytosis assay was performed using F1TC labeled Saccharomyces yeast particles. Phagocytic functional activity was observed in 10-11% of resting THP-1 cells. Treatment of THP-1 cells with LPS of F. nucleatum or P. gingivalis increased the phagocytic activity of THP-1 cells 2-3 fold. GM-CSF significantly increased phagocytosis either alone or when supplemented with LPS of F. nucleatum or P. gingivalis. A chemotaxis assay was performed using a 48 well chemotaxis chamber. Chemotactic functional activity of THP-1 cells was increased 2-fold after 4 days of treatment with GM-CSF. Stimulation of THP-1 cells with LPS of F. nucleatum or P. gingivalis significantly reduced the chemotactic activity indicating the maturation towards a fixed macrophage. There were functional variations (chemotaxis and phagocytosis) in THP-1 cells in response to LPS of oral microorganisms following stimulation with GM-CSF.