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The Health | august-September, 2020
| Hot Topic |
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Sepsis and the immune response
The key to combat sepsis lies in a balanced immune response that produces
enough reaction to kill off pathogens
Everyone in the household has
been down with a bad cough
and flu for the past one week,
including Hana herself. Luckily,
her seven-year-old daughter
seems to be getting better after a
few days of high fever.
She is now almost back to her usual
self, much to Hana’s relief. But not her
elderly father. His fever persists and he
is getting more tired and breathless by
the day. Hana is perplexed. It was only a
simple infection. Why is her father not
getting better when everyone else is?
The immune system
– a military force
Imagine our body as a nation. As a
nation, it ought to be protected from any
form of threats and that responsibility
lies in our defense system. The body’s
military force is known as the immune
system. When an external invader
enters our body as bacteria or virus,
generally known as pathogens, it
triggers two types of immune response
within the complex system.
The first response activated is the
innate immune response, which occurs
within minutes. The cells involve in
this response are non-specific and have
no memory. What it means is that they
do not distinguish one invader from
another and will amount the same
response no matter how many times
they see the pathogen, even if it is the
same type of pathogen.
sepsis
Alert
By Assoc Prof
Dr Tan Toh Leong
and Dr Nurul Huda
Ahmad
This response is responsible for causing
fever. The cells from the innate immune
response will eat up the pathogens and
dissolve them in their own cells. Some
of these cells travel to the nearest lymph
node and present a unique part of the
pathogen to a special cell called T-cell.
Activation of the T-cell unlocks the
second response called adaptive immune
response. This cell is unique for its good
memory and ability to distinguish friendly
pathogens from potentially deadly ones.
A T-cell not only replicates to attack and
eat up pathogens they were presented,
some of the cell stay on as memory cells
to mount a faster and stronger response if
the pathogen invades again in the future.
It will also trigger another sister cell
called B-cell to secrete antibodies towards
the pathogen.
Immune system meltdown
Sepsis occurs when an infection triggers
a series of reactions that injure their own
tissues and organs. The key to combat
sepsis lies in a balanced immune response
that produces enough reaction to kill off
pathogens and at the same time protect its
own tissues and organs.
An exaggerated immune response also
poses danger to our body. Activation of the
innate immune response on a larger scale
causes excessive inflammatory response
called “cytokine storm”. This exorbitant
response damages our organs at the
cellular level leading to impairment of its
function and even failure of the organs.
On the other hand, an immune
response that is too weak to mount an
adequate response to invading pathogens
is also harmful. Many pathogens,
especially bacteria, produce toxins. When
these toxins are released, it is detrimental
to the body as it directly harms the
host tissues leading to cell damage and
dysfunction, which subsequently leads
to organ failure. Immunosuppression or
lack of immune response is often seen
in the elderly, those with diseases that
specifically target immune systems such
as the Human Immunodeficiency Virus
(HIV) or those on medication to fight
certain conditions such as cancer.
Moderation is the key
Our immune system is essential in
protecting us against the unseen
pathogens. It needs, however, to be a
balanced response. Not too much. Not too
little. Just right. Many factors affect our
body immune system. The best way to
optimize our immune system is through
a healthy balanced diet, adequate sleep,
regular physical activity and stress
management. — The Health
Associate Professor Dr Tan Toh Leong is
Senior Lecturer and Consultant Emergency
Physician, Faculty of Medicine, Universiti
Kebangsaan Malaysia, Founder and President
of Malaysian Sepsis Alliance, and Dr Nurul
Huda Ahmad is Lecturer and Emergency
Physician Faculty of Medicine, Universiti
Teknologi MARA.