0000000000896858
AUTHOR
Birgit Oppmann
Alternative assay procedures for cytokines and soluble receptors of the IL-6 family.
Human hepatoma cells (HepG2 cells) were transfected with expression vectors for human IL-6 (hIL-6) and rat IL-6R (rIL-6-R). The cell lines were used for testing the biological activity of different IL-6 species, soluble hIL-6R (shIL-6R) and some members of the IL-6 cytokine family by means of an ELISA procedure. The assay is based on induction of the gene expression of the acute phase protein haptoglobin in hepatoma cells and provides an alternative bioassay taking advantage of the hepatocyte stimulatory activity of IL-6 (as opposed to the B9 proliferative assay). A dose-response experiment with IL-6 showed that half-maximal stimulation was achieved with approx. 5 ng/ml of hIL-6 in HepG2 ce…
A role for the immunoglobulin-like domain of the human IL-6 receptor. Intracellular protein transport and shedding.
Interleukin (IL)-6, IL-11 and cililary neurotrophic factor (CNTF) belong to the same family of hematopoietic and neurotrophic cytokines. Their receptor complexes contain a cytokine-binding alpha receptor and the common glycoprotein (gp)130 subunit for signal transduction. The extracellular parts of the alpha-receptor subunits consist of a membrane-proximal cytokine-binding domain and an N-terminal immunoglobulin (Ig)-like domain with unknown function. We examined the role of the Ig-like domain of IL-6R by constructing deletion mutants lacking the Ig domain (IL-6RDeltaIg and soluble IL-6RDeltaIg). IL-6RDeltaIg was shed as effectively as wild-type IL-6R from transfected COS-7 cells upon 4beta…