Page 95 - The Miracle of the Immune System

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Step By Step To All-Out War

manner ever imaginable. Just like everything else in the universe, our de-
fence system, too, has obeyed its purpose of creation to become an indis-
pensable, critical element of life:
Hearkening to its Lord as it is bound to do…(Surat al-Inshiqaq: 2)

Tolerance
We have explored in previous chapters how the defence system dis-

tinguishes between friendly and hostile cells with the help of the recep-
tors. However, the building blocks of some hostile cells are almost iden-
tical to those of certain tissues in the human body. This represents a sig-
nificant problem for the defence system, which might conceivably attack
some of its own tissues accidentally.
Under normal conditions, though, such a response never happens in
a healthy human body. The defence system never attacks a molecule, cell,
or tissue of its own. In medical terms this phenomenon is referred to as
"tolerance".

This constitutes an extremely important miracle. We can clearly see
that the defence system is fully capable of differentiating between thou-
sands of proteins. For example, the defence system must distinguish the
haemoglobin found in blood from the insulin secreted by the pancreas
and from the vitreous humour contained in the eye, and indeed, from ev-
erything else in the human system. The defence system knows that while
it fights a merciless war against foreign molecules, it must not harm any
tissues belonging to the human body.
For many years, researchers have tried to understand how the de-
fence system has learned to be tolerant towards its own tissues. Yet, de-
tails concerning why the most important lymphocytes, namely, the T and

B cells, do not attack the human body have only been revealed in the last
20 years. The tolerance process, only a small portion of which mankind
has been able to discover as the result of years long research, has been in
operation since the human being came into existence.