Interleukin-
6 (
IL-
6) is a pleiotropic cytokine synthesized by many different cells after appropriate stimulation. IL-
6 binds first to the interleukin-
6 receptor alpha (IL
6-R
![greek small letter alpha greek small letter alpha](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
) and then this complex binds to the signal-transducing gp130
receptor, forming a functional hexameric
receptor complex. We observed by Western blot analysis with anti-IL
6-R
![greek small letter alpha greek small letter alpha](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
two bands of
![not, vert, sim<font color=](http://www.sciencedirect.com/scidirimg/entities/223c.gif)
ilar" title="not, vert, sim
ilar" border="0">80 kDa and
![not, vert, sim<font color=](http://www.sciencedirect.com/scidirimg/entities/223c.gif)
ilar" title="not, vert, sim
ilar" border="0">110 kDa in the rat sciatic nerve, cerebral cortex, spleen, pancreas and liver, corresponding to the mature glycosylated form and possibly to the dimer of the non-glycosylated precursor protein. By immunohistochemistry, high levels of IL
6-R
![greek small letter alpha greek small letter alpha](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
expression are observed in non-myelinating Schwann cells. In myelinating Schwann cells IL
6-R
![greek small letter alpha greek small letter alpha](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
is present as discrete dots in the perinuclear region, in distinct membrane domains of the Schwann cell sheath and at the nodes of Ranvier, suggesting that IL
6-R
![greek small letter alpha greek small letter alpha](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
is clustered both on the axonal side of the node and within the Schwann cells. After sciatic nerve crush injury IL
6-R
![greek small letter alpha greek small letter alpha](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
is upregulated in denervated Schwann cells between the myelin ovoids during the period of Schwann cell proliferation. The expression of IL
6-R
![greek small letter alpha greek small letter alpha](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
continues during the period of remyelination, suggesting that IL
6-R
![greek small letter alpha greek small letter alpha](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
might be involved in both Schwann cell proliferation and remyelination of the rat sciatic nerve.