Immune Diseases

Immune diseases generally refer to autoimmune diseases that are caused by immune system's immune response against body components. The immune system normally responds to foreign intruders like as bacteria, viruses, parasites, and transplants by destroying or repelling them. However, certain conditions might cause abnormalities in the body's tissue components or the immune system itself, causing the immune system to mistake its own components for foreign objects to attack. At this time, the immune system will produce antibodies and active lymphocytes that target some of the body's own components, damaging and destroying its own tissues and organs, ultimately leading to disease. Broadly defined immune diseases also include structural or functional abnormalities of the immune system, which can be congenital or acquired.

Classification of Immune Diseases

The immune system is a sophisticated and highly effective system that shields the human body from alien or hazardous invaders. It is specific, inducible, and adaptive. However, faulty identification or other inherent defects can cause the defensive function to fail and even induce the immune system to attack the body itself. This condition is classified into three categories: immune deficiency, autoimmunity, and hypersensitivity. Common immune diseases are listed as follows:

• Asthma
• Systemic lupus erythematosus
• Rheumatoid arthritis
• Autoimmune thyroid disease
• Inflammatory bowel disease (IBD)
• Allograft rejection
• Graft-versus-host disease
• Primary immunodeficiency

Causes of Immune Diseases

Autoimmune disease means that the body produces an immune response to itself. Autoimmune reactions can occur in a number of ways:

• A normal body substance altered by viruses, drugs, sunlight, or radiation may be recognized by the immune system as a foreign substance. Viruses, for example, can infect and alter cells in the body. Virus-infected cells stimulate the immune system to attack them.
• Foreign substances similar to the body's natural substances can enter the body. The immune system can occasionally target similar body substances as well as foreign substances. For example, the bacteria causing streptococcus throat infection carry antigens that are similar to those found in human heart cells. In rare cases, the immune system attacks a patient's heart after attacking streptococcus in the throat.
• Cells that control antibody production may have abnormal functions and produce abnormal antibodies that attack certain cells of the body.
• Substances that are normally confined to specific parts of the body are released into the bloodstream. For example, eye trauma can result in the release of eyeball fluid into the bloodstream. The fluid stimulates the immune system to identify the eye as foreign and attack it.

Immunodeficiency disease refers to the inability of the body to produce an appropriate immune response to invading microorganisms. The causes of immunodeficiency diseases can be divided into two types:

• Primary Immunodeficiency: Such diseases usually exist at birth and are usually hereditary, which often manifest in infancy or childhood. There are currently more than 100 primary immunodeficiency diseases, but all are relatively rare.
• Secondary Immunodeficiency: These diseases usually occur late in life and are often caused by the use of certain drugs or by other diseases such as diabetes or human immunodeficiency virus (HIV) infection. They are more common than primary immunodeficiency diseases.

An allergic reaction is an excessive immune response to a generally harmless foreign antigen. Allergens may cause allergic reactions after contact with skin or eyes, inhalation, ingestion or injection.

Prevention and Treatment of Immune Diseases

Immune disease prevention and treatment are largely determined by the disease's type and symptoms. Controlling the autoimmune response by inhibiting the immune system is required. It should be noted, however, that many drugs that suppress the immune response will also impair the body's ability to resist disease, especially infection. Prevention is usually the most important factor in immunodeficiency diseases. Furthermore, stem cell transplantation can be used to treat certain immunodeficiency diseases, particularly severe combined immunodeficiency diseases. Stem cells are derived from bone marrow and occasionally blood, and they are frequently employed to treat serious diseases.

For research use only. Not intended for any clinical use.