Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!ginosko!usc!ucla-cs!FUCHS%VCUVAX.BITNET@oac.ucla.edu
From: FUCHS%VCUVAX.BITNET@oac.ucla.edu
Newsgroups: sci.med.aids
Subject: Re:HIV Infection and Chaos
Message-ID: <27922@shemp.CS.UCLA.EDU>
Date: 9 Oct 89 17:37:00 GMT
Sender: news@CS.UCLA.EDU
Lines: 49
Approved: aids@cs.ucla.edu
Archive-number: 1335

Rob Carr's post did initiate many thoughts.....
I too have become interested in what Chaos Theory might be able to tell
us about the immune system (and in particular immune regulation.)
The immune system seems to be a "nonlinear dynamic system."  For example,
the response you get (say amount of antibody produced) is not linearly related
to the amount of antigen used to drive the system.

I admit that I know little about chaos theory and this leaves me open to
'fatal flaws' in the reasoning. However, it seems like the theory of immune
regulation which deals with idiotype networks may respond to this technique.
In the 'Network Hypothesis' the immune system is viewed as constantly
responding in positive and negative ways to various antigen receptors.
The whole spectrum of antigen receptors available in the immune system
act to form "internal images" of the external antigenic world.  That is
to say that the reason the immune system can respond to any antigen found
in the world is that it is ALREADY responding to it, in the form of an
internal image of its three dimensional structure represented in some
cell clone's antigen receptor.  This is very complicated to imagine
for if a specific cell clone was induced to proliferate, it's antigen
receptors would act as positive and negative signals for the
proliferation or suppression of various other cell clones.  When these secondary
clones responded they would in turn affect the behavior of still other clones,
and others, and others.  Hence a 'network.'  Given the vast complexity
of this system it seems that it would be impossible to predict what
effect the proliferation of a single clone might have on the regulation
of the system as a whole.

My thought is then, might there not be a "strange attractor" which constrains
the operation of the above network.  Within these limits the network
appears to oscillate chaotically, yet not beyond the limits imposed by the
attractor.  Impostion of a pathogen like HIV which fundamentally alters
the immune system might then alter the attractor so that the network now
functions under new and dramatically different constraints.

My problem is that I would not know how to set up an experiment to look
for this relationship.  I do not know what to "measure."  Here I am
probably handcuffed by the limited understanding of immune regulation
(on a body wide scale and not simply in response to a single antigen)
which exists today.

I agree with Tom Mandel that I do not see any immediate applications of
chaos theory to HIV infection IN TERMS OF disease PROGRESSION.  It seems
that the progression from HIV infection to seroconversion to AIDS is
fairly well defined and predictable.  (Although the biological basis
for this slow progression is NOT well understood for AIDS or Kuru or
Scrapie and other such painfully slow diseases.)

If any of you have insight into the application of Chaos theory to
biology I would like to hear from you.