|
navigator page
mind stuff
body stuff
soul stuff
love and sex
wealth stuff |
|
MECHANISMS OF ALLERGY Allergy mechanisms are far-reaching and complex, including overload, toxicity, true allergy, intolerance etc. Use this platform to explore different types of allergic mechanisms. You need to read most or all of these to gain a proper understanding of what this section is all about. Remember: more than one mechanism may be operating in your case! IN ANY EVENT, READ THIS INTRODUCTION FIRST, BEFORE YOU JUMP OFF. Unfortunately, we run into a problem
right away, which is that there is no real consensus agreement on exactly what
constitutes an allergic reaction. The water is made muddy by classic
allergists, scared of infringements on their lucrative territory, claiming that
only they deal with “real” allergies.
Their representatives bodies, such as the American College of Allergy and
Immunology, continue to produce position papers, which effectively dismiss any
one else’s view as fraud. But in their eager fury to try to destroy the
competition, they leave vast armies of patients high and dry. To merely negate
anything other than the classical allergy model is to fail to address the many
different and similar mechanisms by which external triggers can cause disease
in unlucky individuals but not in the population at large. I have always worked with the very simple “shorthand” definition of allergy which in layman’s terms is: something you should avoid because you will feel better if you do!” This empirical (hands-on) approach is based on the following clinical criteria:
This is eminently
sensible and is how the term is used today in popular usage. The layman does
not need to know the mechanisms of allergy, hypersensitivity and intolerance
but can readily grasp the concept of ‘something to avoid’.
The
historic view
Let us take an
overview and see if this leads to more understanding, starting with the
historical perspective. The word allergy was first coined by an Austrian
paediatrician, Clemens von Pirquet,
in 1906. He defined an allergy as an acquired, specific, altered capacity to react
to a physical substance on the part of the tissues of the body. This
description is worth considering in more detail : Acquired means that it is not in-born or constitutional, though there is no
doubt that the tendency to allergies runs in families. In what is now
the ‘classic’ allergic reaction, an individual must meet the substance (at
least once) and
the allergy results from this initial sensitizing encounter. Babies that
appear to be born with an allergy do not really conflict with this theory. It’s
just that they made their first contact while in the womb (with, for example, a
food in the mother’s diet). Specific means that it is not a generalized reaction but relates to one exact
substance or, in reality, often a small part of a molecule of that substance.
An individual may react to many things at once but
each reaction is unique. Even if several allergens (allergy-causing substances)
provoke the same effect, it is simply that the final end-organ stimulated is
the same in each case. Altered means the reaction is not ‘normal’. In other words, not everyone shares
the same experience. The majority of our species would probably not react
in the way an allergic patient does. For example, most of us eat tomatoes
safely, yet some people cannot do so without risking a severe asthma attack or
some other unpleasant con-sequence. However, there
are difficulties in this last interpretation. Once you start to move outside
the immunological guidelines for an allergy, phenomena such as an allergy to
wheat become very common. Probably half the population or more don’t tolerate
it anything like as well as they suppose, once you start asking the right questions.
We may retain the adjective ‘altered’ perhaps, but such reactions may be
anything but rare or unusual. Furthermore,
when it comes to a matter such as low-grade poisoning (see below), then substances
that induce symptoms are toxic for everyone. ‘Allergy’ then becomes only a
matter of degree. Sensitive people react to levels of the toxin that would be
tolerated by the average individual. In the 1920s
the sort of reaction von Pirquet was talking about
was commonly found to have an immunological basis, ie.
it was an antigen-antibody phenomenon. Apparently, the
body was responding to foreign protein (and even food is considered ‘foreign’
by the body since it is ‘non-self’) by mounting an antibody attack. The
spin-off from this interaction, rather like fall-out from a chemical battle,
was what gave rise to the unwanted and inappropriate symptoms experienced by
the patient. There is
something radically wrong, however, with this simplistic and narrow definition,
though immunologists cling to it like a raft at sea. The great paradox – as
pointed out by Professor John Soothill (personal
communication) - is
that if this explanation were true, we all ought to get allergic reactions to
food every time we eat. Obviously this doesn’t happen. Somehow the body knows not
to react against food protein. Unfortunately
for those who stand by this rhetoric, even as early as 1920 Dr Albert Rowe and
others were able to demonstrate that there were clear reactions to ingested
substances and that these could be established to exist beyond any doubt,
regardless of the lack of adequate explanation. Since these reactions also
accord with von Pirquet’s original definition, there
seemed nothing wrong with calling them allergy – in this case, food allergy. There was no
real controversy at the time, since Rowe was not an internationally known
figure. He continued his seminal researches, wrote his book Food Allergy: Its Manifestations, Diagnosis and Treatment
(Lea and Febiger, Philadelphia, 1931) and departed
the world stage. However, his successors, notably Randolph, Rinkel
and Zeller, authors of Food Allergy (Charles C. Thomas, Springfield,
Illinois, 1951), carried on Rowe’s work and, particularly since the 1950s, the
proof that dietary allergies could exist without there being any demonstrable
antibodies became steadily more and more compelling – to the embarrassment of
immunologists. If these immunologists admitted the existence of food allergy at
all, they’d say it was ‘very rare’ and applied only to a very tiny minority of
the population. Randolph, Rinkel and Zeller were
finding far too many cases. As the debate hotted up in the 1970s and 1980s the two groups polarized and antagonism grew more unpleasant. To ease the situation, the term ‘food intolerance’ was introduced in a booklet published jointly in 1984 by the Royal College of Physicians and the British Nutrition Foundation. This was an attempt to try and accommodate the fact that unpleasant reactions to food clearly did exist, but nonetheless the die-hard immunologists wouldn’t give in and allow the term ‘allergy’ to be applied. In many ways this was a poor compromise, especially since proponents of the term cannot provide any explanation of how ‘intolerance’ comes about. THERE FOLLOWS THE KEY SECTIONS OF ALLERGIC MECHANISMS AND A BRIEF EXPLANATION:
|
| navigator page mind stuff body stuff soul stuff love and sex wealth stuff |
|