Expression of cytokines IL-4, IL-12, IL-15, IL-18, and IFNγ and modulation by different growth factors in cultured human osteoblast-like cells

The antigenic phenotype of cultured human osteoblast-like cells, their ability to phagocytose particles of different nature and size, and their capacity to stimulate allogeneic T cells suggest that they are related to other cell populations with which they may also have immunological functions in common. The objective of this study was to investigate the intracytoplasmatic presence of cytokines and their modulation by different biomolecules. Immunocytochemistry and flow cytometry were used to study the expression of IL-4, IL-12, IL-15, IL-18, and IFNγ cytokines. To investigate whether FGF, TGF, PDGF, IL-1, and IFNγ modulate expression of these cytokines in cultured human osteoblast-like cells we used flow cytometry. IL-4, IL-12, IL-15, IL-18, and IFNγ cytokines were expressed by all the cultured human osteoblast-like cells studied. Treatment with FGF and TGFβ1 reduced the percentage expression and fluorescence intensity of the cytokines. PDGF treatment enhanced their fluorescence intensity but did not modify their expression. IL-1 treatment produced a small reduction in expression and fluorescence intensity of IL-12 and IL-15, but did not produce major changes in the expression of IL-4, IL-18, or IFNγ. IFNγ markedly increased the fluorescence intensity of the cytokines. The results indicate that human osteoblast-like cells may perform immunological functions (e.g., synthesizing cytokines with immune regulator function) that can be modulated by different biomolecules related to bone tissue and/or immune response.