Re Re Cytokines and taxonomy...

Steve Hopkins shopkins at fs1.ho.man.ac.uk
Thu Feb 2 11:41:39 EST 1995


In article <3gaae0$feh at agate.berkeley.edu> frauwirt at notmendel.Berkeley.EDU (Ken Frauwirth (BioKen)) writes:
>From: frauwirt at notmendel.Berkeley.EDU (Ken Frauwirth (BioKen))
>Subject: Re: Re Re Cytokines and taxonomy...
>Date: 27 Jan 1995 08:21:20 GMT

>In article <ralph.1141524010E at news.arizona.edu>,
>Ralph M Bernstein <ralph at ccit.arizona.edu> wrote:


>      [question about distinction between cytokines and hormones]

>>
>>OK, cytokines all act through a membrane bound receptor.  I think that
>>hormones are membrane soluable and go running in through the outer PM and
>>get bound to an internal binding protein which can then escort or follow
>>into the nucleus. That's a difference. Cytokines activate and work through
>>this membrane bound receptor system and activate a signal transduction
>>pathway-like PKCs ect.  Hormones, when in the nucleus can act
>>directly-binding and inducing transcription much more primarily. Also I
>>think that hormones are usually planar-rings-hydrophobic so they go
>>screaming through the PM, while cytokines are small proteins- many of them
>>homologous to each other. Certainly, I WOULD call the immune system a
>>specific organ, but thats me.  You must also remember that many of the
>>immune system's cytokines/lymphokines have been "stolen" from the
>>developmental biologists, it's just that immunologists may have identified
>>these molecules first.  Example, IL-1 is very important in normal
>>development, as well as playing a role in the mature individual not
>>necessarily always as the endogenous pyrogen. Back to the first point, the
>>main role of  cytokines (in their immune system role) is to play a part in
>>cell-to-cell communication.  
>>
>>
>>Ralph M. Bernstein
>>Dept of Micro/Immuno
>>University of Arizona
>>Ph: 602 626 2585
>>Fx: 602 626 2100

>This is not true at all.  While steroid hormones are membrane soluble and
>act on receptors that are transcription factors, the peptide hormones
>(growth hormone, ACTH, insulin) and amino acid derivatives (serotonin, 
>dopamine, epinephrine) all work through membrane-bound receptors.

>In addition, a number of cytokines have been shown to be non-critical for
>development.  Knockouts of IL-2 and IL-4 have no developmental (or
>immunological) defects.

>However, I agree that the immune system is a true organ system, and it
>seems to me that there is no real conceptual difference between cytokines
>and other hormones.

>BioKen
>-- 
>Ken Frauwirth (MiSTie #33025)       _           _
>frauwirt at mendel.berkeley.edu       |_) *    |/ (_ |\ |
>Dept. of Molec. & Cell Bio.        |_) | () |\ (_ | \|  
>Univ. of Cal., Berkeley          Push the button...someone :(

Absolutely agree about the receptor point. But the immune system as an organ 
seems a bit much. Immunity is a physiological function. It seems rather like 
saying the reproductive system is an organ. The thymus may be an organ, but 
not the whole system (Which just about includes every cell in the body - 
interferon producers!?).

Steve Hopkins



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