Large Molecules - Biotechnology and Your Health: Pharmaceutical Applications - page 37

whole population vaccination programs organized by the World
Health Organization (WHO).
Other immunizations use substances taken from the micro-
organism that causes the disease, and some even use whole killed
disease-causing bacteria. The DPT shots that children receive before
entering school are made up of proteins isolated from the bacteria
that cause diphtheria and whooping cough (pertussis), plus killed
tetanus bacteria. The pertussis and diphtheria proteins used in the
The Immune System—Our Best Defense
The immune system of humans and other animals consists of a series of specialized cells
and proteins that provide powerful defenses against infectious diseases. Immune system
cells develop in the marrow, the soft tissue inside the bones, and in the thymus, a small
organ just in front of the heart. When immune system cells mature, they move to the
spleen, a large organ in the abdomen; to lymph nodes, small organs located throughout
the body; to the appendix; and to the blood. When you have a sore throat or cough and
the doctor pokes and prods your neck, he or she is trying to see if the lymph nodes in
your neck are swollen, which would indicate that they are fighting an infection. You have
probably also heard of tonsils and adenoids, immune system tissues in the throat
and nose that are rich in infection-fighting cells. The purpose of that look into your
throat is to see if your tonsils are swollen and red, another sign that the body is fighting
an infection.
Immune system cells provide both general responses to infections and responses
precisely targeted to the specific infecting virus or bacteria. The infection-specific cells,
called lymphocytes , work to attack and remove infecting pathogens.
Another important defense tool of the immune system consists of specialized
proteins called antibodies , or immunoglobulins, that are produced by lymphocytes and
can recognize and bind to proteins on the surfaces of microorganisms, resulting in their
destruction and removal from the body. The disease-fighting lymphocytes that produce
antibodies are able to “remember” previous exposure to a protein or other substance
and respond quickly if it reappears in the body. Vaccination and other immunizations
that prevent disease cause the immune system to develop the appropriate set of specific
lymphocytes and antibodies that can quickly attack an infection.