T cell deficiency

T cell deficiency
T cell deficiency
	Human T Cell
Specialty	Immunology
Symptoms	Eczematous
Types	Primary or Secondary
Diagnostic method	Delayed hypersensitivity skin test, T cell count
Treatment	Bone marrow transplant, Immunoglobulin replacement

T cell deficiency is a deficiency of T cells, caused by decreased function of individual T cells, it causes an immunodeficiency of cell-mediated immunity.^[1] 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).^{[medical citation needed]}

Symptoms and signs

Presentations differ among causes, but T cell insufficiency generally manifests as unusually severe common viral infections (respiratory syncytial virus, rotavirus), diarrhea, and eczematous or erythrodermatous rashes.^[1] Failure to thrive and cachexia are later signs of a T-cell deficiency.^[1]

Mechanism

In terms of the normal mechanism of T cell we find that it is a type of white blood cell that has an important role in immunity, and is made from thymocytes.^[5] One sees in the partial disorder of T cells that happen due to cell signaling defects, are usually caused by hypomorphic gene defects.^[6] Generally, (micro)deletion of 22Q11.2 is the most often seen.^[7]

Pathogens of concern

The main pathogens of concern in T cell deficiencies are intracellular pathogens, including Herpes simplex virus, Mycobacterium and Listeria.^[8] Also, intracellular fungal infections are also more common and severe in T cell deficiencies.^[8] 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:^[1]^[4]^[3]

Delayed hypersensitivity skin test
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 (SCID), Omenn syndrome, and Cartilage–hair hypoplasia.^[1]
Secondary causes are more common than primary ones.^[9] Secondary (or acquired) causes are mainly:^[9]

Complete or partial deficiency

Complete insufficiency of T cell function can result from hereditary conditions (also called primary conditions) such as severe combined immunodeficiency (SCID), Omenn syndrome, and cartilage–hair hypoplasia.^[1]
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).^[1]

Treatment

In terms of the management of T cell deficiency for those individuals with this condition the following can be applied:^[2]^[1]

Killed vaccines should be used(not live vaccines in T cell deficiency)
Bone marrow transplant
Immunoglobulin 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.^[1] Furthermore, SCID has an incidence of approximately 1 in 66,000 in California.^[10]