cytokines, internalised?

Peter Smith rtfm at
Mon Mar 28 17:39:39 EST 1994

> > 
> Dear netters,
> I know that several (all?) of the growth factors (e.g. NGF) are 
> internalised after they bind to their receptors. But I would
> like to know if this is true for the cytokines as well. I have tried
> looking in several textbooks but can find no mention of such a
> mechanism. Does this mean that the cytokines are not internalised,
> that no one has looked (!), or that it happens but nobody thinks
> that it is important? 
> Any help, information, or pointers to the right place to look in the
> literature would be most welcome.
> Thanks
> Mike Duggan
Hi Mike, 
        There are certainly reports in the literature of a number of 
cytokines which get internalised after binding to high affinity 
receptors. The ones which come to mind for me are IL-2 (have a look at J. 
Exp Med. 163.p550-562 (1986), and more recently P.N.A.S. 90. p4127 
(1993)) and IL-7 (a recent report in Science. 262. p1877), I used to work 
on IL-2, now on IL-7! From what I know internalisation of cytokines is a 
pretty general phenomenon. It probably acts to down-regulate the 
response, (as the receptor gets internalised too). There were also 
suggestions a while ago (in the case of IL-2 anyway) that it may be 
directly involved in cytokine signalling, but this may not be true ie I 
haven't seen anything on this topic in the literature recently. Hope this 

Theresa Page

email: rtfm at

Sunley Building
Kennedy Institute of Rheumatology

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