I’ve often wished the immune system had a
different name. One that sounded a lot more grand and complicated. It
slips easily off the tongue and gulls people into thinking that it’s no more
complicated than their central heating system. And that the equivalent of a
tweak of the thermostat (in the form of a pill or a foot massage) can give “it”
a quick boost. When researching my book I realised that it’s a system of a very different kind – more like, say, the complexity of a city like London with its
workers, businesses, buildings and transport networks.
There are two main divisions to the immune
system. The emergency “innate” division kicks in the minute you have a wound.
On a much slower timescale the “adaptive” division learns about all the
bacteria, viruses and proteins in your environment – which to ignore and which
to attack with antibodies the next time they crop up. There are many different
types of immune cell (“white blood cells”) and new sub-types are discovered regularly.
They produce a vast array of complex proteins called cytokines that also play a
role in attacking pathogens. Part of what we mean by “immune system” is this
interacting mass of cells and proteins that flow through blood and tissues
during health and illness. But there is more. The permanent structures of the
immune system are the bone marrow, which is the production unit for replacement
immune cells, and the lymphatic system that monitors threats throughout the
body.
As in cities, balance is important. You don’t
need a rail system that varies its timetable unpredictably. Neither do you need
an immune system that is over- or under-active. Everything has to be modulated
to keep things running smoothly so as to prevent not only infection but also self-damage.
Diseases associated with an over-active immune system include all the auto-immune
diseases, allergies and inflammatory conditions. Toxic shock, sepsis and the
cytokine storm (which can occur in pandemic flu) are more sudden and much more deadly
over-reactions.
Some illnesses are not just attacked by the
immune system – they directly infect
immune cells and interact with them in complex ways. It’s well known that the
HIV retro-virus directly attacks immune cells, using them as a base and slowly
undermining their work. TB, caused by a bacterium, also infects immune cells – the
ones that normally engulf and destroy bacteria entering the lungs. Ebola too
infects immune cells, and progresses far more swiftly than HIV or TB. It does
so by using infected immune cells to spread the virus throughout the
body. Ebola is also able to damp down aspects of the immune function. But that
is not all. The high fever and inflammation of the later stages of the disease are
part of a massive immune over-reaction that contributes to death.
There are various scientific initiatives
attempting to tackle this unusual virus but the solutions are not simple.
There are some anti-viral drugs undergoing
accelerated trials but it would be surprising if they make a significant
impact. The might of the pharmaceutical industry has yet to produce a range of
wonder-working anti-virals for other diseases. Anti-retrovirals, used for HIV,
are probably the biggest success, despite all their limitations. Vaccine
development is a long and difficult road and vaccines in current development
are a while away from any prospect of a mass
roll-out. The experimental biological treatment ZMapp is a product of
immunological research. It’s a combination of artificially produced antibodies
that lock on to specific targets on the Ebola virus, disabling it. It is to be
hoped that ZMapp works, and that one day it can be produced in large enough
quantities to be useful in bringing outbreaks under control. However production
methods are complex involving a lot of careful work by technicians and the growth of cloned cells in laboratory
conditions. This process is not at all like
the factory production line that produces conventional chemical drugs. My
feeling is that science is very unlikely to come up with any quick answers, with mass impact, in
the next few months.
In the meantime though, simple nursing measures
like infection control and putting up a drip can save lives. As Christmas looms we are asked to
contribute to a wide range of charities but this year many of us will perhaps consider
that paying for some nursing supplies for Ebola stricken areas is the most
urgent call on our generosity.
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