The inflammatory response (inflammation) occurs when tissues are injured by bacteria, trauma, toxins, heat, or any other cause. The damaged cells release chemicals including histamine, bradykinin, and prostaglandins. These chemicals cause blood vessels to leak fluid into the tissues, causing swelling. This helps isolate the foreign substance from further contact with body tissues.

The chemicals also attract white blood cells called phagocytes that "eat" microorganisms and dead or damaged cells. This process is called phagocytosis. Phagocytes eventually die. Pus is formed from a collection of dead tissue, dead bacteria, and live and dead phagocytes.

IMMUNE SYSTEM DISORDERS AND ALLERGIES

Immune system disorders occur when the immune response is inappropriate, excessive, or lacking. Allergies involve an immune response to a substance that most people's bodies perceive as harmless.

For more information, see:

• Allergies
• Autoimmune disorders
• Immunodeficiency disorders

IMMUNIZATION

Vaccination (immunization) is a way to trigger the immune response. Small doses of an antigen, such as dead or weakened live viruses, are given to activate immune system "memory" (activated B cells and sensitized T cells). Memory allows your body to react quickly and efficiently to future exposures.

COMPLICATIONS DUE TO AN ALTERED IMMUNE RESPONSE

An efficient immune response protects against many diseases and disorders. An inefficient immune response allows diseases to develop. Inadequate, inappropriate, or excessive immune response causes immune system disorders.

Complications related to altered immune responses include:

• Allergy or hypersensitivity
• Anaphylaxis
• Autoimmune disorders
• Blood transfusion reaction
• Disease development
• Graft versus host disease
• Immunodeficiency disorders
• Serum sickness
• Transplant rejection

Images

Immune response

Phagocytosis

Phagocytosis

Vaccines

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Immune response Prevention

Review Date: 05/02/2010
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)