Description:
<jats:p>In human body fluids a soluble form of the interleukin‐6 receptor (sIL‐6R) has been found which together with interleukin‐6 (IL‐6) acts agonistically on cells expressing the signal transducer gp130. The means by which the sIL‐6R is removed from the circulation is unknown. Here, we show that a complex of <jats:sup>125</jats:sup>I‐labelled recombinant sIL‐6R and IL‐6 is internalized by MDCK cells stably transfected with gp130 and by human hepatoma cells HepG2 that endogenously express the IL‐6R and gp130. We further show that most of the internalized sIL‐6R is degraded within lysosomes. Our studies suggest that cells expressing gp130 are capable of endocytosing an IL‐6/sIL6R complex, thereby removing both from the circulation.</jats:p>