Refers to a state in which the immune system’s ability to fight infectious disease is compromised or entirely absent.
May also decrease cancer immunosurveillance.
Most cases are acquired, but some people have primary immunodeficiency.
A person who has an immunodeficiency of any kind is said to be immunocompromised.
Immunocompromised patients are vulnerable to opportunistic infections, and to the usual infections that affect everyone.
Patients taking medications to suppress their immune system as an anti-rejection measure, or for an over-active system are immunocompromised..
There are a number of types of immunodeficiency classified by the affected component: humoral, T cell deficiency, granulocyte deficiency, asplenia, and complement deficiency.
Humoral immune deficiency, with signs or symptoms including signs of hypogammaglobulinemia with repeated mild respiratory infections, and/or agammaglobulinemia which results in frequent severe infections that may be fatal.
T cell deficiency, often causes secondary disorders such as acquired immune deficiency syndrome.
Granulocyte deficiency, including decreased numbers of granulocytes such as neutropenia or agranulocytosis.
Granulocyte deficiencies also include decreased function of individual granulocytes, such as in chronic granulomatous disease.
Asplenia, where there is no function of the spleen
Complement deficiency
Immunodeficiency often affects multiple components. with notable examples including severe combined immunodeficiency and acquired immune deficiency syndrome.
Primary immunodeficiency refers to a number of rare diseases feature a heightened susceptibility to infections from childhood onward.
Also known as congenital immunodeficiencies, many of these disorders are hereditary and are autosomal recessive or X-linked.
Presently over 80 recognized primary immunodeficiency syndromes; generally categorized by the part of the immune system that is malfunctioning, such as lymphocytes or granulocytes.
The treatment of primary immunodeficiencies may involve immunoglobulin infusions, antibiotics and stem cell transplantation.
Secondary immunodeficiencies, which acquired immunodeficiencies, can result from malnutrition, aging, chemotherapy, disease-modifying antirheumatic drugs, immunosuppressive drugs after organ transplants, and glucocorticoids.
Many types of cancer directly or indirectly cause immunosuppression, particularly those of the hematopoietic cells, and certain chronic infections do the same.
Immunodeficiency is also the hallmark of acquired immunodeficiency syndrome (AIDS) due to the human immunodeficiency virus (HIV).
HIV directly infects a small number of T helper cells, and also impairs other immune system responses indirectly.
Immunodeficiency syndromes may present with clinical and laboratory characteristics of autoimmunity, and it is suggested the impaired ability of the immune system to clear infections in these patients may be responsible for causing autoimmunity by the perpetual immune system activation.
In the common variable immunodeficiency (CVID) multiple autoimmune diseases are present, suchas inflammatory bowel disease, autoimmune thrombocytopenia and autoimmune thyroid disease.
Pancytopenia, rashes, lymphadenopathy and hepatosplenomegaly are common in common variable immunodeficiency.
X-linked agammaglobulinemia (XLA) associated with chronic and/or recurrent infections, arthritis, autoimmune hemolytic anemia, scleroderma and type 1 diabetes.
Recurrent bacterial and fungal infections and chronic inflammation of the gut and lungs are seen in chronic granulomatous disease (CGD).
Chronic granulomatous disease is caused by decreased production of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase by neutrophils.
Wiskott-Aldrich syndrome patients present with eczema, autoimmune manifestations, recurrent bacterial infections and lymphoma.
In autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) autoimmunity and infections coexist: with organ-specific autoimmune manifestations including hypoparathyroidism and adrenocortical failure, and chronic mucocutaneous candidiasis.
IgA deficiency is also sometimes associated with the development of autoimmune and atopic phenomena.