Liver cells can be induced by interleukin-1, tumor necrosis factor and interleukin-6 to secrete higher amounts of complement components. Information, so far available only for the early components, indicates that these cytokines exhibit different effects on various complement proteins. For instance, they promote the biosynthesis of C3 and B but have no effect on that of C4 and C2. These observations led us to evaluate the ability of interleukin-1, tumor necrosis factor and interleukin-6 to modulate the secretion of the late complement components by HepG2 cells, a human hepatoma-derived cell line known to produce several complement proteins. The amount of complement components in the culture supernatant was evaluated by a sensitive enzyme-linked immunosorbent assay revealing picogram levels of these proteins. The HepG2 cells were found to secrete a substantial amount of C3 (approximately 1μg/106 cells), easily detectable C5 (approximately 150 ng/106 cells) and C8 (approximately 10 ng/106 cells) and a low amount of C6 (approximately 0.5 ng/106 cells), whereas the levels of both C7 and C9 could not be measured. The addition of interleukin-1, tumor necrosis factor and interleukin-6 to the cell culture resulted in an enhanced secretion of C8, whereas that of C5 was only marginally increased. None of these cytokines had a clear effect on the secretion of C6 nor induced the production of C7 and C9. The magnitude of increased levels of C3 and C8 in the culture medium was related to the cytokine used, since interleukin-6 induced a more substantial response of C8 than interleukin-1, and, conversely, interleukin-1 was more effective than interleukin-6 in enhancing the secretion of C3. No clear differences were found in the amount of the various components secreted in response to tumor necrosis factor.
|Number of pages||4|
|Journal||International Journal of Clinical & Laboratory Research|
|Publication status||Published - Jan 1994|
- Complement secretion
- HepG2 cells
ASJC Scopus subject areas
- Clinical Biochemistry