In medicine, immune deficiency (or immunodeficiency) is a state where the immune system is incapable of defending the organism from infectious disease. There are roughly two types: congenital and acquired immune deficiency.

Congenital immune deficiency

A large number of rare diseases has been described that feature a heightened susceptibility to infections from childhood onward. Most of these disorders are hereditary and autosomal recessive. Defects are either of the humoral immunity, cell-mediated immunity or combined (such as in severe combined immunodeficiency—SCID).

Most congenital immune deficiencies are rare. Other examples include myeloperoxidase deficiency, Wiskott-Aldrich syndrome and chronic granulomatous disease.

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. This feature is used to suppress immune activity in autoimmune disorders with DMARDs. Any drug that causes neutropenia and/or agranulocytosis can cause immune suppression and sepsis.

Immune deficiency is also the hallmark of Acquired Immunodeficiency Syndrome (AIDS). AIDS invades CD4⁺-T-lymphocytes (Helper T cells), leading to opportunistic infections.

See also

• Immune system