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 (IL6-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-IL6-R
![greek small letter alpha greek small letter alpha](http://www.sciencedirect.com/scidirimg/entities/204e.gif)
two bands
of ![not, vert, similar not, vert, similar](http://www.sciencedirect.com/scidirimg/entities/223c.gif)
80 kDa and
![not, vert, similar not, vert, similar](http://www.sciencedirect.com/scidirimg/entities/223c.gif)
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 IL6-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 IL6-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 IL6-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 IL6-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 IL6-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 IL6-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.