T cell deficiency
Encyclopedia
T cell deficiency is a deficiency
of T cell
s, either caused by lymphocytopenia
of T cells or by decreased function of individual T cells. It causes an immunodeficiency
of cell-mediated immunity
.
(SCID), Omenn syndrome
, and Cartilage-hair hypoplasia
.
Causes of partial insufficiencies of T cell function include acquired immune deficiency syndrome (AIDS), and hereditary conditions such as DiGeorge syndrome
(DGS), chromosomal breakage syndromes (CBSs), and B-cell and T-cell combined disorders such as ataxia telangiectasia
(AT) and Wiskott-Aldrich syndrome
(WAS).
of T cells include some that cause complete insufficiency of T cells, such as severe combined immunodeficiency
(SCID), Omenn syndrome
, and Cartilage-hair hypoplasia
.
Secondary (or acquired) causes are mainly:
Overall, secondary causes are more common than primary ones.
can, in turn, be classified as:
Peripheral (or non-thymic) causes of T cell deficiency include: Purine nucleoside phosphorylase deficiency
, hyper IgM syndrome
(in turn including, for example, 1)
, Mycobacterium
and Listeria. Also, intracellular fungal infections are also more common and severe in T cell deficiencies.
Other intracellular pathogens of major concern in T cell deficiency are:
, rotavirus
), mucocutaneous candidiasis, diarrhea
, and eczema
tous or erythroderma
tous rashes. Failure to thrive
and cachexia
are late signs of a T-cell defect.
Deficiency (medicine)
In medicine, a deficiency is a lack or shortage of a functional entity, by less than normal or necessary supply or function.-Nutrients:Malnutrition can cause various effects by deficiency of one or more nutrients...
of T cell
T cell
T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity. They can be distinguished from other lymphocytes, such as B cells and natural killer cells , by the presence of a T cell receptor on the cell surface. They are...
s, either caused by lymphocytopenia
Lymphocytopenia
Lymphocytopenia, or lymphopenia, is the condition of having an abnormally low level of lymphocytes in the blood. Lymphocytes are a white blood cell with important functions in the immune system...
of T cells or by decreased function of individual T cells. It causes an immunodeficiency
Immunodeficiency
Immunodeficiency is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Immunodeficiency may also decrease cancer immunosurveillance. Most cases of immunodeficiency are acquired but some people are born with defects in their immune system,...
of cell-mediated immunity
Cell-mediated immunity
Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages, natural killer cells , antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen...
.
By complete versus partial deficiency
Complete insufficiency of T cell function can result from hereditary conditions (also called primary conditions) such as severe combined immunodeficiencySevere combined immunodeficiency
Severe combined immunodeficiency , is a genetic disorder in which both "arms" of the adaptive immune system are impaired due to a defect in one of several possible genes. SCID is a severe form of heritable immunodeficiency...
(SCID), Omenn syndrome
Omenn syndrome
Omenn syndrome is an autosomal recessive severe combined immunodeficiency associated with mutations in the recombination activating genes , affecting circulating levels of both B-cells and T-cells.-Symptoms:...
, and Cartilage-hair hypoplasia
Cartilage-hair hypoplasia
Cartilage–hair hypoplasia , also known as McKusick type metaphyseal chondrodysplasia, is a rare form of short-limbed dwarfism due to skeletal dysplasia. It was first reported in 1965 by McKusick et al...
.
Causes of partial insufficiencies of T cell function include acquired immune deficiency syndrome (AIDS), and hereditary conditions such as DiGeorge syndrome
DiGeorge syndrome
22q11.2 deletion syndrome, which has several presentations including DiGeorge syndrome , DiGeorge anomaly, velo-cardio-facial syndrome, Shprintzen syndrome, conotruncal anomaly face syndrome, Strong syndrome, congenital thymic aplasia, and thymic hypoplasia is a syndrome caused by the deletion of a...
(DGS), chromosomal breakage syndromes (CBSs), and B-cell and T-cell combined disorders such as ataxia telangiectasia
Ataxia telangiectasia
Ataxia telangiectasia is a rare, neurodegenerative, inherited disease that affects many parts of the body and causes severe disability. Ataxia refers to poor coordination and telangiectasia to small dilated blood vessels, both of which are hallmarks of the disease...
(AT) and Wiskott-Aldrich syndrome
Wiskott-Aldrich syndrome
Wiskott–Aldrich syndrome is a rare X-linked recessive disease characterized by eczema, thrombocytopenia , immune deficiency, and bloody diarrhea . It is also sometimes called the eczema-thrombocytopenia-immunodeficiency syndrome in keeping with Aldrich's original description in 1954...
(WAS).
Primary versus secondary
Primary (or hereditary) immunodeficienciesPrimary immunodeficiency
Primary immunodeficiencies are disorders in which part of the body's immune system is missing or does not function properly. To be considered a primary immunodeficiency, the cause of the immune deficiency must not be secondary in nature...
of T cells include some that cause complete insufficiency of T cells, such as severe combined immunodeficiency
Severe combined immunodeficiency
Severe combined immunodeficiency , is a genetic disorder in which both "arms" of the adaptive immune system are impaired due to a defect in one of several possible genes. SCID is a severe form of heritable immunodeficiency...
(SCID), Omenn syndrome
Omenn syndrome
Omenn syndrome is an autosomal recessive severe combined immunodeficiency associated with mutations in the recombination activating genes , affecting circulating levels of both B-cells and T-cells.-Symptoms:...
, and Cartilage-hair hypoplasia
Cartilage-hair hypoplasia
Cartilage–hair hypoplasia , also known as McKusick type metaphyseal chondrodysplasia, is a rare form of short-limbed dwarfism due to skeletal dysplasia. It was first reported in 1965 by McKusick et al...
.
Secondary (or acquired) causes are mainly:
- Marrow and other transplantation
- AIDSAIDSAcquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...
- Cancer chemotherapy
- LymphomaLymphomaLymphoma is a cancer in the lymphatic cells of the immune system. Typically, lymphomas present as a solid tumor of lymphoid cells. Treatment might involve chemotherapy and in some cases radiotherapy and/or bone marrow transplantation, and can be curable depending on the histology, type, and stage...
- GlucocorticoidGlucocorticoidGlucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...
therapy
Overall, secondary causes are more common than primary ones.
Thymic versus peripheral
Causes of T cell deficiency by thymic hypoplasiaThymic hypoplasia
Thymic hypoplasia is a condition where the thymus is underdeveloped or involuted.Calcium levels can be used to distinguish between the following two conditions associated with thymic hypoplasia:* 22q11.2 deletion syndrome: hypocalcemia...
can, in turn, be classified as:
- hypoparathyroid (such as Di George's syndromeDiGeorge syndrome22q11.2 deletion syndrome, which has several presentations including DiGeorge syndrome , DiGeorge anomaly, velo-cardio-facial syndrome, Shprintzen syndrome, conotruncal anomaly face syndrome, Strong syndrome, congenital thymic aplasia, and thymic hypoplasia is a syndrome caused by the deletion of a...
) - euparathyroid (Such as Nezelof syndromeNezelof syndromeNezelof syndrome is an autosomal recessive congenital immunodeficiency condition due to underdevelopment of the thymus.An association with CD44 has been proposed.-History:...
and Ataxia telangiectasiaAtaxia telangiectasiaAtaxia telangiectasia is a rare, neurodegenerative, inherited disease that affects many parts of the body and causes severe disability. Ataxia refers to poor coordination and telangiectasia to small dilated blood vessels, both of which are hallmarks of the disease...
)
Peripheral (or non-thymic) causes of T cell deficiency include: Purine nucleoside phosphorylase deficiency
Purine nucleoside phosphorylase deficiency
Purine nucleoside phosphorylase deficiency, often called PNP-deficiency, is a rare autosomal recessive metabolic disorder which results in severe combined immunodeficiency.-Signs and symptoms:...
, hyper IgM syndrome
Hyper IgM syndrome
Hyper IgM syndrome is a family of genetic disorders in which the level of Immunoglobulin M antibodies is relatively high. The most common type is a result of a defect in a Th2 cell protein . The disorder causes immunodeficiencies, including a higher than normal susceptibility to various types of...
(in turn including, for example, 1)
Pathogens of concern
The main pathogens of concern in T cell deficiencies are intracellular pathogens, including Herpes simplex virusHerpes simplex virus
Herpes simplex virus 1 and 2 , also known as Human herpes virus 1 and 2 , are two members of the herpes virus family, Herpesviridae, that infect humans. Both HSV-1 and HSV-2 are ubiquitous and contagious...
, Mycobacterium
Mycobacterium
Mycobacterium is a genus of Actinobacteria, given its own family, the Mycobacteriaceae. The genus includes pathogens known to cause serious diseases in mammals, including tuberculosis and leprosy...
and Listeria. Also, intracellular fungal infections are also more common and severe in T cell deficiencies.
Other intracellular pathogens of major concern in T cell deficiency are:
- Mycobacterium avium intracellulare
- SalmonellaSalmonellaSalmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...
species - Rhodococcus equiRhodococcus equiRhodococcus equi is a Gram-positive coccobacillus bacterium. The organism is commonly found in dry and dusty soil and can be important for diseases of domesticated animals . The frequency of infection can reach near 60 percent. R. equi is an important pathogen causing pneumonia in foals. Since...
- Pneumocystis jiroveciiPneumocystis jiroveciiPneumocystis jirovecii is a yeast-like fungus of the genus Pneumocystis. The causative organism of Pneumocystis pneumonia, it is an important human pathogen, particularly among immunocompromised hosts. Prior to its discovery as a human-specific pathogen, P. jirovecii was known as P...
- Toxoplasma gondiiToxoplasma gondiiToxoplasma gondii is a species of parasitic protozoa in the genus Toxoplasma. The definitive host of T. gondii is the cat, but the parasite can be carried by many warm-blooded animals . Toxoplasmosis, the disease of which T...
- Cryptosporidium parvumCryptosporidium parvumCryptosporidium parvum is one of several protozoal species that cause cryptosporidiosis, a parasitic disease of the mammalian intestinal tract....
- LeishmaniaLeishmaniaLeishmania is a genus of Trypanosomatid protozoa, and is the parasite responsible for the disease leishmaniasis. It is spread through sandflies of the genus Phlebotomus in the Old World, and of the genus Lutzomyia in the New World. Their primary hosts are vertebrates; Leishmania commonly infects...
species - HerpesviridaeHerpesviridaeThe Herpesviridae are a large family of DNA viruses that cause diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word herpein , referring to the latent, recurring infections typical of this group of viruses...
, mainly herpes simplexHerpes simplexHerpes simplex is a viral disease caused by both Herpes simplex virus type 1 and type 2 . Infection with the herpes virus is categorized into one of several distinct disorders based on the site of infection. Oral herpes, the visible symptoms of which are colloquially called cold sores or fever...
, cytomegalovirusCytomegalovirusCytomegalovirus is a viral genus of the viral group known as Herpesviridae or herpesviruses. It is typically abbreviated as CMV: The species that infects humans is commonly known as human CMV or human herpesvirus-5 , and is the most studied of all cytomegaloviruses...
and varicella zoster - Cryptococcus neoformansCryptococcus neoformansCryptococcus neoformans is an encapsulated yeast that can live in both plants and animals. Its teleomorph is Filobasidiella neoformans, a filamentous fungus belonging to the class Tremellomycetes. It is often found in pigeon excrement....
- Histoplasma capsulatum
- Systemic yeast infections
Presentations
Presentations differ among causes, but T cell insufficiency generally manifests as unusually severe common viral infections (e.g. by respiratory syncytial virus (RSV), enterovirusEnterovirus
Enteroviruses are a genus of ssRNA viruses associated with several human and mammalian diseases. Serologic studies have distinguished 66 human enterovirus serotypes on the basis of antibody neutralization tests. Additional antigenic variants have been defined within several of the serotypes on the...
, rotavirus
Rotavirus
Rotavirus is the most common cause of severe diarrhoea among infants and young children, and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five,...
), mucocutaneous candidiasis, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, and eczema
Eczema
Eczema is a form of dermatitis, or inflammation of the epidermis . In England, an estimated 5.7 million or about one in every nine people have been diagnosed with the disease by a clinician at some point in their lives.The term eczema is broadly applied to a range of persistent skin conditions...
tous or erythroderma
Erythroderma
Erythroderma is an inflammatory skin disease with erythema and scaling that affects nearly the entire cutaneous surface....
tous rashes. Failure to thrive
Failure to thrive
Failure to thrive is a medical term which is used in both pediatric and adult human medicine, as well as veterinary medicine ....
and cachexia
Cachexia
Cachexia or wasting syndrome is loss of weight, muscle atrophy, fatigue, weakness, and significant loss of appetite in someone who is not actively trying to lose weight...
are late signs of a T-cell defect.