Immunodeficiency

Immunodeficiency
Classification & external resources

ICD-10	D84.9
ICD-9	279.3
DiseasesDB	21506
MeSH	D007153

In medicine, immunodeficiency (or immune deficiency) is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Most cases of immunodeficiency are either congenital or acquired. A person who has an immunodeficiency is said to be immunocompromised. An immunocompromised person is very vulnerable to opportunistic infections. Boys more often than girls can have immune deficiency. Mostly immune deficiency is recognized in the early ages unless it is an acquired immune deficiency.

Congenital (or Primary) immune deficiency

A number of rare diseases feature a heightened susceptibility to infections from childhood onward. Many of these disorders are hereditary and autosomal recessive.

For more details on this topic, see Primary immunodeficiency.

The following is a list of the congenital immunodeficiencies organized by the immune component that is impaired or missing.

• B cell deficiencies
  • X-linked agammaglobulinemia
  • Selective Immunoglobulin Deficiency

• T cell deficiencies
  • DiGeorge's syndrome (Thymic aplasia)
  • Chronic mucocutaneous candidiasis
  • Hyper-IgM syndrome
  • Interleukin-12 receptor deficiency

• Combined T cell & B cell abnormalities
  • Severe Combined Immunodeficiency Disease (SCID)
  • Wiskott-Aldrich syndrome
  • Ataxia-telangiectasia

• Complement Deficiencies
  • Hereditary Angioedema or Hereditary angioneurotic edema
  • Recurrent Infections
  • Autoimmune-like diseases
  • Paroxysmal nocturnal hemoglobinuria

• Phagocyte deficiencies
  • Leukocyte adhesion deficiency
  • Chronic Granulomatous Disease (CGD)
  • Chédiak-Higashi syndrome
  • Job's syndrome (Hyper-IgE syndrome)
  • Cyclic neutropenia
  • Myeloperoxidase deficiency
  • Glucose-6-phosphate dehydrogenase deficiency
  • Interferon-γ deficiency

• Various / Unknown
  • Common Variable Immunodeficiency (CVID)
  • Vici syndrome

Acquired immune deficiency

Although elderly people are generally more susceptible to infections, this can be increased in the presence of a number of blood disorders (see hematology); important examples are multiple myeloma and chronic lymphatic leukemia (CLL).

Immune suppression is a common side-effect of many drugs, most importantly chemotherapy. However, Disease-modifying antirheumatic drugs (DMARDs) are used to suppress immune activity in autoimmune disorders to slow progression of this type of disease. Any drug that causes neutropenia or agranulocytosis can cause immune suppression and sepsis. Organ transplant recipients are given immunosuppressive drugs to avoid transplant rejection.

Immune deficiency is also the hallmark of Acquired Immunodeficiency Syndrome (AIDS), caused by a virus, Human immunodeficiency virus (HIV). HIV destroys CD4⁺-T-lymphocytes (Helper T cells), which play a critical role in modulating immune response, and the loss of these immune cells leads eventually to immunocompromise and opportunistic infections.

Biochemistry

In all higher mammals a complex set of biochemicals is present that regulates the immune system. Imbalances of these chemicals by nutritional deficit, disease or infection can compromise the immune system.