Immune System

Immune system is the most dynamic body component in determining our state of health or disease. Our immune system constantly interacts with our internal environment, protects us from our external environment and provides the inherent knowledge to sense the difference between friend and foe.

Everyday our immune system must overcome viruses, bacteria, fungi and parasites. It neutralizes toxins. It protects us from cancer everyday. It knows the difference between friend and enemy. It’s constantly interacting with our “internal” and “external” environment.

The immune system is made up of a network of cells, tissues, and organs that work together to protect the body. The cells involved are white blood cells, or leukocytes, which come in two basic types that combine to seek out and destroy disease-causing organisms or substances.

The two basic types of leukocytes are:
1.phagocytes, cells that chew up invading organisms
2.lymphocytes, cells that allow the body to remember and recognize previous invaders and help the body destroy them

When your body encounters a germ, its first line of defense is your immune system. Specialized cells and organs help your body recognize and respond to foreign invaders. Your immune system even has its own circulatory system, called the lymphatic system.

If your immune system cannot do its job, the results can be serious. Disorders of the immune system include
•Allergy and asthma - inappropriate immune responses to substances that are usually harmless
•Graft-vs.-host disease - a life-threatening reaction in people receiving organ transplants
•Immune deficiency diseases - disorders in which your resistance to disease becomes dangerously low
•Autoimmune diseases - diseases causing your immune system to attack your own body's cells and tissues by mistake


Immunity can be strong or weak, short-lived or long-lasting, depending on the type of antigen it encounters, the amount of antigen, and the route by which the antigen enters the body. Immunity can also be influenced by inherited genes. When faced with the same antigen, some individuals will respond forcefully, others feebly, and some not at all.

An immune response can be sparked not only by infection but also by immunization with vaccines. Some vaccines contain microorganisms—or parts of microorganisms— that have been treated so they can provoke an immune response but not full-blown disease.
Immunity can also be transferred from one individual to another by injections of serum rich in antibodies against a particular microbe (antiserum). For example, antiserum is sometimes given to protect travelers to countries where hepatitis A is widespread. The antiserum induces passive immunity against the hepatitis A virus. Passive immunity typically lasts only a few weeks or months.

Infants are born with weak immune responses but are protected for the first few months of life by antibodies they receive from their mothers before birth. Babies who are nursed can also receive some antibodies from breast milk that help to protect their digestive tracts.

For many years, healthcare providers have used vaccination to help the body’s immune system prepare for future attacks. Vaccines consist of killed or modified microbes, parts of microbes, or microbial DNA that trick the body into thinking an infection has occurred.

A vaccinated person’s immune system attacks the harmless vaccine and prepares for invasions against the kind of microbe the vaccine contained. In this way, the person becomes immunized against the microbe. Vaccination remains one of the best ways to prevent infectious diseases, and vaccines have an excellent safety record. Previously devastating diseases such as smallpox, polio, and whooping cough (pertussis) have been greatly controlled or eliminated through worldwide vaccination programs.

Inherited immune system disorders are diseases in which children are born without an immune system or with an incomplete immune system. People with an immune system disorder are less able to fight infections.

Inherited immune system disorders are also called primary immune deficiency disorders. They are called "primary" because they are caused by a gene defect that affects the immune system. Genes carry an inherited code of instructions that tells the body how to make every cell and protein in the body. (Secondary immune deficiencies are caused by something outside the body, such as chemotherapy or infection with a virus.)

People with severe inherited immune system disorders are at high risk for life-threatening infections. For many severe disorders, the only known cure is a bone marrow or cord blood transplant (also called a BMT). The following are two of the most severe inherited immune system disorders:
•Severe Combined Immunodeficiency (SCID) and Transplant
•Wiskott-Aldrich Syndrome (WAS) and Transplant

Transplant has also been used to treat some other inherited immune system disorders, including:
•Combined immunodeficiency associated with other syndromes: Severe DiGeorge Syndrome, X-linked immunodeficiency with normal or elevated IgM, X-linked lymphoproliferative disease, IPEX (Immune dysregulation, Polyendocrinopathy, Enteritis, and X-linked) syndrome
•Humoral immunodeficiency: Common variable immunodeficiency
•Other deficiencies: Chronic granulomatous disease, leukocyte adhesion deficiency

To find out whether transplant is a treatment option for you or your family member, talk to a doctor who is an expert in treating these.