CELLS INFECTED WITH THE COMMON COLD VIRUS.
FROM UPI/BETTMANN NEWSPHOTOS, THE IMMUNE SYSTEM
I'm sure you can remember the last time you had a cold. Or how you caught the flu last Christmas while visiting Aunt Sue. Almost everyone has gotten sick at some point in their life. Luckily, almost everyone has an immune system. Your immune system
destroys disease causing agents that enter your body. Without your immune system, you would die. You can blame sickness on microscopic invaders called antigens. Any foreign object to the body is an antigen. Not all of these things are harmful, but a
few are. However, not all antigens are bad. In fact, your body has two kinds of self antigens. Your immune system consists of a whole lot of defenses against disease. One such defense is phagocytes.
CELLS INFECTED WITH THE COMMON COLD VIRUS.
FROM UPI/BETTMANN NEWSPHOTOS, THE IMMUNE SYSTEM
Phagocytes are white blood cells. They destroy germs and antigens. If you fell and cut your arm, and germs got into your blood, blood phagocytes (polymorphonuclear cells) would head directly toward the infected area and would eat them, using killer enzy mes (proteins that accelerate reaction. Large phagocytes assemble and consume the dead cells, debris, and remaining bacteria.
Macrophages and granulocytes are phagocytes. Granulocytes ingest foreign invaders when coated with immunoglobulin or complement proteins in the blood. Macrophages act like granulocytes, but they do something else, too. They change the antigens in a way
that makes the immune response more effective. They process the antigens they consume so they can be attacked by B and T cells.
A MACROPHAGE OVERCOMES AND EATS A CANCER CELL.
FROM THE UPJOHN COMPANY, THE IMMUNE SYSTEM
B and T cells are very important parts of the immune system. B cells produce antibodies so they are partly responsible for humoral immunity. B cells depend mostly on T cells to begin the attack because they have less receptors than the T cell, so can on ly recognize a few antigens. Once a B cell recognizes an antigen, it multiplies, becomes a plasma cell, and starts producing antibodies that fight a specific antigen. They produce antibodies until T cells signal for them to stop. The antibodies attack and "kill" the antigen.
T cells are responsible for cellular immunity. There are several kind of T cells. A helper T cell activates the immune system by giving off a signal that puts antibody-producing B cells and other cells into action. A suppresser T cell controls the immu
ne response so the body won't be overwhelmed. The killer T cells destroys antigen carriers and any foreign object- including transplanted organs. MHC (major histocompatibility complex) triggers attacks against invaders. T cells won't respond to an anti
gen unless a MHC protein is on the surface of the cell.
A COMPUTER-GENERATED ANTIBODY ATTACK
FROM COMPUTER GRAPHIC MODELING AND PHOTOGRAPHY BY ARTHUR J. OLSON,SCRIPPS CLINIC, THE IMMUNE SYSTEM
Antibodies are part of a group called immunoglobulins. Thousands of different antibodies are made to fight each different antigen. Antibodies are protein molecules that counteract the effect of antigens. After being formed, antibodies are circulated in the blood. There are five classes of antibodies. Each have different jobs.
A lymphocyte is yet another cell found in the immune system. There are two kinds of lymphocytes. T lymphocytes and B lymphocytes have different jobs.
A LYMPHOCYTE
FROM PHOTO RESEARCHERS, YOUR IMMUNE SYSTEM
B CELL LYMPHOCYTES
FROM ROGER ULRICH, PH.D/THE UPJOHN COMPANY, THE IMMUNE SYSTEM
Cytokines are soluble components responsible for keeping the immune response regular.
Complement proteins are another part of the immune response. When an antibody attaches to an antigen, complement proteins join this complex, allowing the antigen to be destroyed. Complement proteins play a large part in the immune response also.
Somewhere along the line, the immune system gets the disease under control. A suppressive process takes place to shut down the immune response. If the immune system cannot overtake the disease, the person that has it will die. Someone can be born with a faulty one or even none at all. In these rare cases, special attention must be given.
Researchers today are trying to discover a way to manipulate, or control, the immune system. It's a good thing we have immune systems. Otherwise, the common cold would be deadly. The question you should think about is "What would we do without our immune systems?" The answer is, absolutely nothing.