Knowing What Can Go Wrong with Your Immune System - dummies

Knowing What Can Go Wrong with Your Immune System

The human species wouldn’t have survived long if the body had no immune system. The first cold virus would have made the original members of our fair species extinct right away, if the body’s immune system didn’t fight off that invading cold virus. Your immune system is your body’s defense department, and it is active in both times of health and illness. Your immune system protects your body from invading microbes, such as bacteria and viruses, other foreign cells, and your own cells that have gone bad (such as cancer cells).

The fine line between healthy and diseased can be crossed when a problem arises in the immune system. Some immune system disorders are evident immediately; others exist for years before any signs or symptoms occur.

The three main types of immune system disorders are

  • Autoimmune diseases
  • Allergies
  • Immunodeficiencies

Autoimmune diseases

Autoimmune diseases occur when your immune system attacks your own “self” cells. Some bacteria and viruses produce toxins that cause T cells (thymus-derived cell) to attack the body’s own proteins on the surface of the macrophage instead of the microbe’s antigen that’s inside the macrophage. Eventually, killer T cells start to view other cells in the body as foreign. Some diseases thought to be initiated in this manner include lupus erythematosus, rheumatoid arthritis, multiple sclerosis, and myasthenia gravis.

Lupus erythematosus

Lupus affects connective tissue, causing an arthritis-like condition. The two major types of lupus are Discoid lupus erythematosus (DLE), which affects connective tissues in the skin, and systemic lupus erythematosus (SLE), which affects several of the body’s systems. Because SLE is much more common, this section focuses on SLE, which waxes and wanes through periods of attack (usually during spring and summer) and times of remission. The disease affects mostly women. An infection with a streptococcal bacterium or a virus, as well as pregnancy, ultraviolet light, stress, and faulty estrogen metabolism can cause lupus.

People with SLE experience flulike symptoms and pain in several joints (polyarthralgia). Chest pain, difficulty breathing, low blood pressure, and tachycardia (rapid heart beat) occur in about half of SLE patients. Signs that neurologic damage has occurred include seizures, depression, irritability, headaches, and mood swings. Urinary tract infections and kidney failure are the most common causes of death in people with SLE. There is no cure for lupus. Treatment often includes corticosteroid medications, such as prednisone, and medications to prevent problems in the kidneys and blood vessels.

Rheumatoid arthritis

Inflammation caused by a person’s immune system attacking its own cells eventually damages cartilage, and then joints. This type of damage occurs in people with rheumatoid arthritis. Rheumatoid refers to the condition of rheumatism, which consists of inflammation, degeneration, and limited movement of structures made of connective tissue (such as joints and tendons). Flulike symptoms and development of joint inflammation ranging from swelling to destruction of bone, followed by atrophy, deformities, and loss of mobility, signal the disease. It usually begins in the fingers, but also can occur in other joints of the arms and legs, including the ankles, knees, wrists, and elbows.

The predisposition to developing rheumatoid arthritis runs in families. Hormone levels also may affect the development of the disease. Rheumatoid arthritis affects mostly women, starting between the ages of 35 and 50. There is no cure. Treatment consists of anti-inflammatory medications and pain relievers. Immunosuppressants (drugs that suppress the immune system to prevent the body from attacking its own cells) can be used early in the disease. Exercise and physical therapy help to retain a range of motion in the joints. As the disease progresses, surgery often becomes necessary to realign bones and reduce pain. Replacement of joints may be needed.


Allergens cause the immune system to have a hypersensitivity reaction. If certain allergens, such as pet dander, dust, or pollen, make you itch, break out in hives, have a runny nose (rhinitis), or make your eyes water, then you’ve experienced a hypersensitivity reaction. Allergies can go through cycles. Some allergies are seasonal, such as hay fever, whereas others occur year-round (such as food allergies). The severity of allergies can change from year to year, some allergies stop after a certain amount of time, and some start late in life without prior problems with a substance. Genetics can predispose people to allergies.

IgE (immunoglobulin E) antibodies, which cause the release of histamine, initiate allergic reactions. Histamine causes swelling of mucous membranes, such as in the nose and throat. The swelling causes nasal congestion and that annoying itch in the throat that you can’t scratch. Congestion and swelling can trap bacteria in the nasal cavities and lead to sinus infections or ear infections.

A severe allergic reaction that causes sudden breathing difficulty is anaphylaxis. These reactions can lead to shock (anaphylactic shock) or death. People with severe allergies to foods, such as shellfish or peanuts, can experience these frightening reactions. Treatment is an epinephrine injection. Tracheotomy (creating a hole through the throat and trachea so that air can enter) sometimes is necessary if the tissues in the throat swell, obstructing airflow. Tissues lining the bronchial tubes of the lungs also can swell, obstructing airflow through the lungs. Respiratory failure, shock, and arrhythmias of the heart (altered rhythm of heart beat) can lead to death rapidly, so knowing the signs of anaphylaxis and acting quickly can save someone’s life if their immune system begins to cross that fine line between health and disease.


AIDS is caused by the human immunodeficiency virus (HIV). HIV targets helper T cells, which makes a person infected with HIV unable to fight against this virus — a real Catch-22. Over time, the immune system of an HIV-positive person becomes deficient in helper T cells, creating an immunodeficiency (a deficiency of a part of the immune system). This immunodeficiency is acquired (rather than induced) through lifestyle choices (such as unprotected sex, intravenous drug use) or events (such as blood transfusion) that expose a person to HIV. The presence of HIV and the deficiency of helper T cells that develops because of infection by the virus usually causes an affected person to acquire diseases, such as pneumonia.

After having HIV in their body for a period of time — and becoming immunodeficient — people usually develop the disease called acquired immunodeficiency syndrome (AIDS). When a person progresses from being HIV-positive to actually having AIDS, they tend to become infected with bacteria and viruses easily, and cancer can occur (such as Kaposi’s sarcoma). A cure for AIDS hasn’t been found yet, and treatment is expensive and still mostly experimental.