Immune System and Disorders (2024)

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Summary

What is the immune system?

Your immune system is a complex network of cells, tissues, and organs. Together they help the body fight infections and other diseases.

When germs such as bacteria or viruses invade your body, they attack and multiply. This is called an infection. The infection causes the disease that makes you sick. Your immune system protects you from the disease by fighting off the germs.

What are the parts of the immune system?

The immune system has many different parts, including:

  • Your skin, which can help prevent germs from getting into the body
  • Mucous membranes, which are the moist, inner linings of some organs and body cavities. They make mucus and other substances which can trap and fight germs.
  • White blood cells, which fight germs
  • Organs and tissues of the lymph system, such as the thymus, spleen, tonsils, lymph nodes, lymph vessels, and bone marrow. They produce, store, and carry white blood cells.

How does the immune system work?

Your immune system defends your body against substances it sees as harmful or foreign. These substances are called antigens. They may be germs such as bacteria and viruses. They might be chemicals or toxins. They could also be cells that are damaged from things like cancer or sunburn.

When your immune system recognizes an antigen, it attacks it. This is called an immune response. Part of this response is to make antibodies. Antibodies are proteins that work to attack, weaken, and destroy antigens. Your body also makes other cells to fight the antigen.

Afterwards, your immune system remembers the antigen. If it sees the antigen again, it can recognize it. It will quickly send out the right antibodies, so in most cases, you don't get sick. This protection against a certain disease is called immunity.

What are the types of immunity?

There are three different types of immunity:

  • Innate immunity is the protection that you are born with. It is your body's first line of defense. It includes barriers such as the skin and mucous membranes. They keep harmful substances from entering the body. It also includes some cells and chemicals which can attack foreign substances.
  • Active immunity, also called adaptive immunity, develops when you are infected with or vaccinated against a foreign substance. Active immunity is usually long-lasting. For many diseases, it can last your entire life.
  • Passive immunity happens when you receive antibodies to a disease instead of making them through your own immune system. For example, newborn babies have antibodies from their mothers. People can also get passive immunity through blood products that contain antibodies. This kind of immunity gives you protection right away. But it only lasts a few weeks or months.

What can go wrong with the immune system?

Sometimes a person may have an immune response even though there is no real threat. This can lead to problems such as allergies, asthma, and autoimmune diseases. If you have an autoimmune disease, your immune system attacks healthy cells in your body by mistake.

Other immune system problems happen when your immune system does not work correctly. These problems include immunodeficiency diseases. If you have an immunodeficiency disease, you get sick more often. Your infections may last longer and can be more serious and harder to treat. They are often genetic disorders.

There are other diseases that can affect your immune system. For example, HIV is a virus that harms your immune system by destroying your white blood cells. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome). People with AIDS have badly damaged immune systems. They get an increasing number of severe illnesses.

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Symptoms

Diagnosis and Tests

Treatments and Therapies

Related Issues

Specifics

Genetics

  • 22q11.2 deletion syndrome: MedlinePlus Genetics Immune System and Disorders (21) (National Library of Medicine)
  • Activated PI3K-delta syndrome: MedlinePlus Genetics Immune System and Disorders (22) (National Library of Medicine)
  • Adenosine deaminase deficiency: MedlinePlus Genetics Immune System and Disorders (23) (National Library of Medicine)
  • Anhidrotic ectodermal dysplasia with immune deficiency: MedlinePlus Genetics Immune System and Disorders (24) (National Library of Medicine)
  • Autosomal dominant hyper-IgE syndrome: MedlinePlus Genetics Immune System and Disorders (25) (National Library of Medicine)
  • Bare lymphocyte syndrome type I: MedlinePlus Genetics Immune System and Disorders (26) (National Library of Medicine)
  • Bare lymphocyte syndrome type II: MedlinePlus Genetics Immune System and Disorders (27) (National Library of Medicine)
  • Chediak-Higashi syndrome: MedlinePlus Genetics Immune System and Disorders (28) (National Library of Medicine)
  • Chronic granulomatous disease: MedlinePlus Genetics Immune System and Disorders (29) (National Library of Medicine)
  • Common variable immune deficiency: MedlinePlus Genetics Immune System and Disorders (30) (National Library of Medicine)
  • Complement component 2 deficiency: MedlinePlus Genetics Immune System and Disorders (31) (National Library of Medicine)
  • Complement component 8 deficiency: MedlinePlus Genetics Immune System and Disorders (32) (National Library of Medicine)
  • Complement factor I deficiency: MedlinePlus Genetics Immune System and Disorders (33) (National Library of Medicine)
  • DOCK8 immunodeficiency syndrome: MedlinePlus Genetics Immune System and Disorders (34) (National Library of Medicine)
  • Erdheim-Chester disease: MedlinePlus Genetics Immune System and Disorders (35) (National Library of Medicine)
  • Familial candidiasis: MedlinePlus Genetics Immune System and Disorders (36) (National Library of Medicine)
  • Familial hemophagocytic lymphohistiocytosis: MedlinePlus Genetics Immune System and Disorders (37) (National Library of Medicine)
  • Griscelli syndrome: MedlinePlus Genetics Immune System and Disorders (38) (National Library of Medicine)
  • Hepatic veno-occlusive disease with immunodeficiency: MedlinePlus Genetics Immune System and Disorders (39) (National Library of Medicine)
  • Immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome: MedlinePlus Genetics Immune System and Disorders (40) (National Library of Medicine)
  • IRAK-4 deficiency: MedlinePlus Genetics Immune System and Disorders (41) (National Library of Medicine)
  • JAK3-deficient severe combined immunodeficiency: MedlinePlus Genetics Immune System and Disorders (42) (National Library of Medicine)
  • Langerhans cell histiocytosis: MedlinePlus Genetics Immune System and Disorders (43) (National Library of Medicine)
  • Leukocyte adhesion deficiency type 1: MedlinePlus Genetics Immune System and Disorders (44) (National Library of Medicine)
  • Mannose-binding lectin deficiency: MedlinePlus Genetics Immune System and Disorders (45) (National Library of Medicine)
  • MDA5 deficiency: MedlinePlus Genetics Immune System and Disorders (46) (National Library of Medicine)
  • Omenn syndrome: MedlinePlus Genetics Immune System and Disorders (47) (National Library of Medicine)
  • PGM3-congenital disorder of glycosylation: MedlinePlus Genetics Immune System and Disorders (48) (National Library of Medicine)
  • Poikiloderma with neutropenia: MedlinePlus Genetics Immune System and Disorders (49) (National Library of Medicine)
  • Primary Immune Deficiency Disease Genetics and Inheritance Immune System and Disorders (50) (National Institute of Allergy and Infectious Diseases)
  • Purine nucleoside phosphorylase deficiency: MedlinePlus Genetics Immune System and Disorders (51) (National Library of Medicine)
  • Spondyloenchondrodysplasia with immune dysregulation: MedlinePlus Genetics Immune System and Disorders (52) (National Library of Medicine)
  • Systemic mastocytosis: MedlinePlus Genetics Immune System and Disorders (53) (National Library of Medicine)
  • T-cell immunodeficiency, congenital alopecia, and nail dystrophy: MedlinePlus Genetics Immune System and Disorders (54) (National Library of Medicine)
  • TRNT1 deficiency: MedlinePlus Genetics Immune System and Disorders (55) (National Library of Medicine)
  • Vici syndrome: MedlinePlus Genetics Immune System and Disorders (56) (National Library of Medicine)
  • Wiskott-Aldrich syndrome: MedlinePlus Genetics Immune System and Disorders (57) (National Library of Medicine)
  • X-linked agammaglobulinemia: MedlinePlus Genetics Immune System and Disorders (58) (National Library of Medicine)
  • X-linked hyper IgM syndrome: MedlinePlus Genetics Immune System and Disorders (59) (National Library of Medicine)
  • X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection, and neoplasia: MedlinePlus Genetics Immune System and Disorders (60) (National Library of Medicine)
  • X-linked lymphoproliferative disease: MedlinePlus Genetics Immune System and Disorders (61) (National Library of Medicine)
  • X-linked severe combined immunodeficiency: MedlinePlus Genetics Immune System and Disorders (62) (National Library of Medicine)
  • Yao syndrome: MedlinePlus Genetics Immune System and Disorders (63) (National Library of Medicine)
  • ZAP70-related severe combined immunodeficiency: MedlinePlus Genetics Immune System and Disorders (64) (National Library of Medicine)

Videos and Tutorials

  • Immune response Immune System and Disorders (65) (Medical Encyclopedia) Also in Spanish
  • Phagocytosis Immune System and Disorders (66) (Medical Encyclopedia) Also in Spanish

Test Your Knowledge

Statistics and Research

Clinical Trials

Children

Teenagers

Patient Handouts

  • Agammaglobulinemia (Medical Encyclopedia) Also in Spanish
  • Aging changes in immunity (Medical Encyclopedia) Also in Spanish
  • Chronic granulomatous disease (Medical Encyclopedia) Also in Spanish
  • Graft-versus-host disease (Medical Encyclopedia) Also in Spanish
  • Histiocytosis (Medical Encyclopedia) Also in Spanish
  • Hyperimmunoglobulin E syndrome (Medical Encyclopedia) Also in Spanish
  • Immune response (Medical Encyclopedia) Also in Spanish
  • Immunodeficiency disorders (Medical Encyclopedia) Also in Spanish
  • Selective deficiency of IgA (Medical Encyclopedia) Also in Spanish
Immune System and Disorders (2024)

FAQs

How do you fix a weak immune system? ›

Every part of your body, including your immune system, functions better when protected from environmental assaults and bolstered by healthy-living strategies such as these:
  1. Don't smoke.
  2. Eat a diet high in fruits and vegetables.
  3. Exercise regularly.
  4. Maintain a healthy weight.
Mar 28, 2024

What are signs that your immune system is fighting a virus? ›

Signs Your Body Is Fighting a Cold
  • Body aches.
  • Congestion.
  • Cough.
  • Decreased appetite.
  • Fatigue.
  • Feeling rundown or unwell.
  • Mild headache.
  • Low-grade fever (99 F to 100.3 F)
Jul 24, 2023

Why is my body not fighting off infections? ›

Immune deficiencies can result from inherited or spontaneous genetic variations, from medications that suppress the immune system, or from infections that damage components of the immune system.

What is the most common immune disorder? ›

While there are more than 100 different kinds of autoimmune disorders, the most common ones include: Inflammatory bowel disease (Crohn's disease, ulcerative colitis) Rheumatoid arthritis (RA) Lupus.

What are the signs of an overactive immune system? ›

Some conditions caused by an overactive immune system are:
  • Asthma. The response in your lungs can cause coughing, wheezing, and trouble breathing. ...
  • Eczema. An allergen causes an itchy rash known as atopic dermatitis.
  • Hay fever (allergic rhinitis). ...
  • Food allergy.

What are the top 5 worst autoimmune diseases? ›

What Are The Most Serious Autoimmune Diseases?
  • Giant Cell Myocarditis. Giant cell myocarditis is a very rare autoimmune disorder causing inflammation of the heart. ...
  • Vasculitis. ...
  • Multiple sclerosis (MS) ...
  • Lupus. ...
  • Anti-NMDA receptor encephalitis.

What are two signs your immune system is working? ›

Signs of a strong immune system

People with a strong immune system are more likely to recover quickly from an injury or illness, feel less fatigue and have good gut health.

How do you know if you have a compromised immune system? ›

Signs and symptoms of primary immunodeficiency can include: Frequent and recurrent pneumonia, bronchitis, sinus infections, ear infections, meningitis or skin infections. Inflammation and infection of internal organs. Blood disorders, such as low platelet count or anemia.

How do you get rid of all infections in your body? ›

How is an Infection Treated?
  1. Antibiotics may be used to treat bacterial infections.
  2. Antifungals may be used to treat fungal infections.
  3. Supportive measures (such as pain relief, decongestants) may be used to treat some viral infections.
  4. Anthelminthics may be used to treat parasitic infections.

How to boost your immune system quickly? ›

Six Tips to Enhance Immunity
  1. Eat Well. Food Assistance. ...
  2. Be Physically Active. Reduced Risk of Death. ...
  3. Maintain a Healthy Weight. Excess weight can affect how your body functions. ...
  4. Get Enough Sleep. ...
  5. Quit Smoking. ...
  6. Avoid Too Much Alcohol. ...
  7. In Summary.

What does an autoimmune flare-up feel like? ›

Common Autoimmune Disease Symptoms

Fatigue. Joint pain and swelling. Skin problems. Abdominal pain or digestive issues.

What is a Type 4 immune disorder? ›

Type four hypersensitivity reaction is a cell-mediated reaction that can occur in response to contact with certain allergens resulting in what is called contact dermatitis or in response to some diagnostic procedures as in the tuberculin skin test.

What are the most common immunodeficiency disorders? ›

Common variable immune deficiency (CVID), previously known as adult-onset hypogammaglobulinemia, is one of the most frequently diagnosed primary immunodeficiencies. It is characterized by low levels of serum antibodies, which cause an increased susceptibility to infection.

What are disorders of immune regulation? ›

Primary immune regulatory disorders (PIRDs) are a group of diseases belonging to inborn errors of immunity. They usually exhibit lymphoproliferation, autoimmunities, and malignancies, with less susceptibility to recurrent infections.

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