In article <3otbq3$e6g at lyra.csx.cam.ac.uk>, mrc7 at cus.cam.ac.uk (Dr M.R. Clark)
writes:
>> is previously cthoburn
> is previously mrclark
>> 1) Parasitism does not mean death. An organism may well carry a parasite
load and be perfectly able to survive.
>Yes but this state of balance normally requires a functioning immune system.
I agree that this is usually true.
>> 2) I do not agree with you that the FUNCTION of immune systems is to protect
an organism from 'undesirables'. I have always been bothered by this concept,
finding no reason at all to beleive that the immune system 'protects' one from
anything. It is true that it is far easier to envision oneself as separate
>I find your reaSoning difficult to understand. Individuals of most higher
species studied who are born with or acquire a major immunodeficiency die very
quickly unless maintained in germ free environments. To say the immune sytem
is unnecessary seems quite a ridiculous statement.
I never said that I felt the immune system was unnecessary, rather I said that
I don't beleive that the 'function' of the immune system is to 'protect' the
individual from 'undesirables'. This is quite different. I think that the
role may be closer to 'providing a mechanism of control over the interaction of
an individual with other organsims'.
>>(...the line between 'self' and 'non-self'... must be an
arbitrary discrimination...)
>Where I would start to agree with you in part is that the arguments about
self/non-self are ideas imposed upon the study of the immune system by
immunologists. Much classical immunology is based upon experiments where
tissues are tranplanted from one animal to another or effector cells are asked
to descriminate in-vitro between self or non-self tissues infected with
virus etc. Clearly these situations are "artificial" and not generally
encountered as the immune system evolved. However that doesn't mean
to say we can't use the results from these studies to interpret the
normal role of the immune system.
Actually I think that this is flawed logic. These types of results can be used
to generate a better guess at how components of the immune system may work, but
I don't think one should assume that the components necessarily work the same
once assembled. I think that interpretation of the 'normal' role of the immune
system must be drawn from experiments on a 'normal' immune system.
Chris Thoburn
