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''
* of
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 r ...
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 ...
of
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 in ...
.
[ 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 rotavirus a ...
), 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 wi ...
, and eczema
Dermatitis is inflammation of the Human skin, skin, typically characterized by itchiness, erythema, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become lichenification, thick ...
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 applie ...
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 f ...
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 cell (biology), 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 de ...
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 thym ...
. 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 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 para ...
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 human ''Herpesviridae'' family, a set of viruses that produce viral inf ...
'', ''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 ...
'' 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 ...
* 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 diffe ...
(SCID), Omenn syndrome
Omenn syndrome is an autosomal recessive severe combined immunodeficiency. It is associated with hypomorphic mutation, hypomorphic missense mutations in immunologically relevant genes of T-cells (and B-cells) such as recombination activating genes ...
, 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 1965 ...
.[
* ''Secondary causes'' are more common than primary ones.] Secondary (or acquired) causes are mainly:[Page 432](_blank)
Chapter 22, Table 22.1 in:
:*AIDS
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 ...
:*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 enlar ...
:*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 vertebr ...
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 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 diffe ...
(SCID), Omenn syndrome
Omenn syndrome is an autosomal recessive severe combined immunodeficiency. It is associated with hypomorphic mutation, hypomorphic missense mutations in immunologically relevant genes of T-cells (and B-cells) such as recombination activating genes ...
, 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 1965 ...
.[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 ma ...
(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 in ...
(DGS), chromosomal breakage syndromes (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 eczem ...
(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 produce ...
* 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
* 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.]
See also
* B cell deficiency
Humoral immune deficiencies are conditions which cause impairment of humoral immunity, which can lead to immunodeficiency. It can be mediated by insufficient number or function of B cells, the plasma cells they differentiate into, or the antib ...
References
Further reading
*
External links
Pubmed
{{Medicine
Immunodeficiency
Immune system disorders
Infection-related cutaneous conditions
Lymphocytes
Lymphocytic disorders
Hematopathology