Page 14 - The Miracle of the Immune System

efore delving into the astounding details of the war of defence
fought in the innermost recesses of our bodies, we must first have
a general look at the defence system and its elements.

Briefly, the defence system may be defined as "an extremely disci-
plined, hard-working and organized army that protects the body from the
clutches of external enemies." In this multi-faceted war, the main duty of
the elements fighting in the front line is to prevent the enemy cells, such
as bacteria or viruses, from entering the body.
Although it is not easy for the enemy organisms to enter the body,
they exert themselves to the utmost to reach their ultimate goal of invad-
ing the body. When they successfully do so, after overcoming various ob-
stacles such as the skin, and the respiratory and digestive tracts, they will
find tough warriors waiting for them. These tough warriors are produced
and trained in specialized centres such as the bone marrow, spleen, thy-
mus, and lymph nodes. These warriors are "the defence cells" referred to
as the macrophages and lymphocytes.
First, various types of phagocytes, which are called the "the eater

cells" will swing into action. Then the macrophages, another specific type
of phagocytes, take their turn. They all destroy the enemy by engulfing it.
Macrophages also perform other duties such as summoning other defence
cells to the battleground, and raising the body temperature. The rise in