Antigen activation of THP-1 human monocytic cells after stimulation with lipopolysaccharide from oral microorganisms and granulocyte-macrophage colony-stimulating factor

A human THP-1 monocyte cell line culture system has been utilized to evalua te the morphological changes in THP-1 cells and to measure expression of ac tivation antigens (CD-11b, CD-11c, CD-14, CD-35, CD-68, CD-71 and HLA-DR) a s evidence of maturation of THP-1 cells in response to stimulation by lipop olysaccharide (LPS) from the oral microorganisms, Fusobacterium nucleatum a nd Porphyromonas gingivalis, and granulocyte-macrophage colony-stimulating factor. THP-1 cells were stimulated with LPS (1 mu g/ml) of P. gingivalis o r F. nucleatum for different time periods (1, 2, 4 and 7 d). Detection of d ifferent activation antigens on THP-I cells was performed by indirect immun ohistochemical staining followed by light microscopy. Confirmational studie s were performed in parallel using indirect immunofluorescence and immunogo ld electron microscopy for detection of the corresponding activation antige ns. Expression of different activation antigens by resting THP-1 cells reve aled HLA-DR to be on 3% of the cells; CD-11b, 9%; CD-11c, 8%; CD-14, 22%; C D-35, 9% and CD-68, 7%. The CD-71 activation antigen was not expressed in u ntreated THP-1 cells. LPS stimulation increased expression of all activatio n antigens. A significant (p < 0.05) increase in expression of CD-11b, CD-1 1c, CD-14, CD-35, CD-68 and CD-71 was observed when GM-CSF (50 IU/ml) was s upplemented during the treatment of THP-1 cells with LPS of F. nucleatum or P. gingivalis. Activation and differentiation of THP-1 cells by LPS from o ral microorganisms in the presence of GM-CSI: supports a role for human mac rophages in acute and chronic periodontal diseases and may explain the clin ically observable periodontal exacerbations in some patients after GM-CSF t herapy.