Page 79 - The Miracle in the Immune System

Cells On Duty In The System 77

In immune individ-
uals, killer T cells
attack and destroy
cells bearing a for-
eign antigen, such
as virus-infected
or cancerous
cells. These T
cells have storage
vacuoles that con-
tain a chemical
called perforin
because it perfo-
rates cell mem-
branes. During the
killing process,
the vacuoles in a T
cell fuse with the
cell membrane
and release units
of the protein per-
forin. These units
combine to form
pores in the target
membrane.
Thereafter, fluid
and salts enter so
that the target cell
eventually bursts.

placed in sacs located in the cell membrane of the lym-
phocytes. This helps the chemical weapon to be used
easily. The lymphocyte injects this toxin only when it
contacts the enemy cell, eventually killing it.
The lymphocytes come in two types: B cells and T
cells.

The Weapon Factories
Of The Human Body: The B Cells
Some of the lymphocytes produced in the bone mar-
row depart when they mature and become fully function-
al, and are transported to the lymphatic tissues through