T cell deficiency is a

deficiency A deficiency is generally a lack of something. It may also refer to: *A deficient number, in mathematics, a number ''n'' for which ''σ''(''n'') < 2''n'' * T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell ...

s, caused by decreased function of individual T cells, it causes an

immunodeficiency Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...

cell-mediated immunity Cell-mediated immunity or cellular immunity is an immune response that does not involve antibodies. Rather, cell-mediated immunity is the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines ...

. T cells normal function is to help with the human body's immunity, they are one of the two primary types of lymphocytes(the other being

B cells B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or ...

Symptoms and signs

Presentations differ among causes, but T cell insufficiency generally manifests as unusually severe common

viral infection A viral disease (or viral infection) occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells. Structural Characteristics Basic structural characteristics, s ...

s (

respiratory syncytial virus Respiratory syncytial virus (RSV), also called human respiratory syncytial virus (hRSV) and human orthopneumovirus, is a common, contagious virus that causes infections of the respiratory tract. It is a negative-sense, single-stranded RNA virus. ...

rotavirus ''Rotavirus'' is a genus of double-stranded RNA viruses in the family ''Reoviridae''. Rotaviruses are the most common cause of diarrhoeal disease among infants and young children. Nearly every child in the world is infected with a rotaviru ...

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin ...

, and

eczema Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can v ...

tous or

erythroderma Erythroderma is an inflammatory skin disease with redness and scaling that affects nearly the entire cutaneous surface.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. p. 436. . This term applies ...

tous rashes.

Failure to thrive Failure to thrive (FTT), also known as weight faltering or faltering growth, indicates insufficient weight gain or absence of appropriate physical growth in children. FTT is usually defined in terms of weight, and can be evaluated either by a low ...

and

cachexia Cachexia () is a complex syndrome associated with an underlying illness, causing ongoing muscle loss that is not entirely reversed with nutritional supplementation. A range of diseases can cause cachexia, most commonly cancer, congestive heart fai ...

are later signs of a T-cell deficiency.

Mechanism

In terms of the ''normal'' mechanism of T cell we find that it is a type of

white blood cell White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...

that has an important role in immunity, and is made from

thymocytes A Thymocyte is an immune cell present in the thymus, before it undergoes transformation into a T cell. Thymocytes are produced as stem cells in the bone marrow and reach the thymus via the blood. Thymopoiesis describes the process which turns thymo ...

. One sees in the ''partial'' disorder of T cells that happen due to

cell signaling In biology, cell signaling (cell signalling in British English) or cell communication is the ability of a cell to receive, process, and transmit signals with its environment and with itself. Cell signaling is a fundamental property of all cellula ...

defects, are usually caused by

hypomorphic Hermann J. Muller (1890–1967), who was a 1946 Nobel Prize winner, coined the terms amorph, hypomorph, hypermorph, antimorph and neomorph to classify mutations based on their behaviour in various genetic situations, as well as gene interact ...

gene defects. Generally, (micro)deletion of 22Q11.2 is the most often seen.

Pathogens of concern

The main pathogens of concern in T cell deficiencies are

intracellular pathogen Intracellular parasites are microparasites that are capable of growing and reproducing inside the cells of a host. Types of parasites There are two main types of intracellular parasites: Facultative and Obligate. Facultative intracellular pa ...

s, including ''

Herpes simplex virus Herpes simplex virus 1 and 2 (HSV-1 and HSV-2), also known by their taxonomical names ''Human alphaherpesvirus 1'' and ''Human alphaherpesvirus 2'', are two members of the Herpesviridae#Human herpesvirus types, human ''Herpesviridae'' family, a ...

'', ''

Mycobacterium ''Mycobacterium'' is a genus of over 190 species in the phylum Actinomycetota, assigned its own family, Mycobacteriaceae. This genus includes pathogens known to cause serious diseases in mammals, including tuberculosis (''M. tuberculosis'') and l ...

'' and ''

Listeria ''Listeria'' is a genus of bacteria that acts as an intracellular parasite in mammals. Until 1992, 17 species were known, each containing two subspecies. By 2020, 21 species had been identified. The genus is named in honour of the British pi ...

''.Page 435
in: Also, intracellular

fungal infections Fungal infection, also known as mycosis, is disease caused by fungi. Different types are traditionally divided according to the part of the body affected; superficial, subcutaneous, and systemic. Superficial fungal infections include common ti ...

are also more common and severe in T cell deficiencies. Other intracellular pathogens of major concern in T cell deficiency are:

Diagnosis

The diagnosis of T cell deficiency can be ascertained in those individuals with this condition via the following: * Delayed hypersensitivity

skin test A skin test is a medical test in which a substance is injected into the skin. Examples * Casoni test * Corneometry * Dick test * Fernandez reaction * Frei test * Hair perforation test * Kveim test * Leishmanin skin test * Lepromin * Patch ...

* T cell count * Detection via culture(infection)

Types

Primary or secondary

* '' Primary (or hereditary) immunodeficiencies'' of T cells include some that cause complete insufficiency of T cells, such as

severe combined immunodeficiency Severe combined immunodeficiency (SCID), also known as Swiss-type agammaglobulinemia, is a rare genetic disorder characterized by the disturbed development of functional T cells and B cells caused by numerous genetic mutations that result in dif ...

(SCID),

Omenn syndrome Omenn syndrome is an autosomal recessive severe combined immunodeficiency. It is associated with hypomorphic missense mutations in immunologically relevant genes of T-cells (and B-cells) such as recombination activating genes (RAG1 and RAG2), I ...

, and

Cartilage–hair hypoplasia Cartilage–hair hypoplasia (CHH) is a rare genetic disorder. Symptoms may include short-limbed dwarfism due to skeletal dysplasia, variable level of immunodeficiency, and predisposition to cancer. It was first reported by Victor McKusick in 19 ...

. * ''Secondary causes'' are more common than primary ones. Secondary (or acquired) causes are mainly:Page 432
Chapter 22, Table 22.1 in: :* AIDS :*

Cancer chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemothera ...

Lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enl ...

Glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every verte ...

therapy

=Complete or partial deficiency

= * ''Complete insufficiency'' of T cell function can result from

hereditary condition A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders ...

s (also called primary conditions) such as

(SCID),

, and

cartilage–hair hypoplasia Cartilage–hair hypoplasia (CHH) is a rare genetic disorder. Symptoms may include short-limbed dwarfism due to skeletal dysplasia, variable level of immunodeficiency, and predisposition to cancer. It was first reported by Victor McKusick in 19 ...

.Medscape > T-cell Disorders
Author: Robert A Schwartz, MD, MPH; Chief Editor: Harumi Jyonouchi, MD. Updated: May 16, 2011 * ''Partial insufficiencies'' of T cell function include

acquired immune deficiency syndrome Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual m ...

(AIDS), and hereditary conditions such as

DiGeorge syndrome DiGeorge syndrome, also known as 22q11.2 deletion syndrome, is a syndrome caused by a microdeletion on the long arm of chromosome 22. While the symptoms can vary, they often include congenital heart problems, specific facial features, frequent ...

(DGS),

chromosomal breakage syndrome Chromosome instability syndromes are a group of inherited conditions associated with chromosomal instability and breakage. They often lead to an increased tendency to develop certain types of malignancies. The following chromosome instability synd ...

s (CBSs), and B-cell and T-cell combined disorders such as ataxia-telangiectasia (AT) and

Wiskott–Aldrich syndrome Wiskott–Aldrich syndrome (WAS) is a rare X-linked recessive disease characterized by eczema, thrombocytopenia (low platelet count), immune deficiency, and bloody diarrhea (secondary to the thrombocytopenia). It is also sometimes called the ecz ...

(WAS).

Treatment

In terms of the management of T cell deficiency for those individuals with this condition the following can be applied: * Killed vaccines should be used(not ''live vaccines'' in T cell deficiency) *

Bone marrow transplant Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to produ ...

Immunoglobulin An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

replacement *

Antiviral therapy Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do no ...

* Supplemental nutrition

Epidemiology

In the U.S. this defect occurs in about 1 in 70,000, with the majority of cases presenting in early life. Furthermore, SCID has an incidence of approximately 1 in 66,000 in California.

References

External links

Pubmed
{{Medicine Immunodeficiency Immune system disorders Infection-related cutaneous conditions Lymphocytes Lymphocytic disorders Hematopathology

Symptoms and signs

Mechanism

Pathogens of concern

Diagnosis

Types

Primary or secondary

=Complete or partial deficiency

Treatment

Epidemiology

See also

References

Further reading

External links