T cell deficiency

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T cell deficiency is a deficiency of T cells, either caused by lymphocytopenia of T cells or by decreased function of individual T cells. It causes an immunodeficiency of cell-mediated immunity.

Classifications of causes

By complete versus 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]

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).[1]

Primary versus 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 (or acquired) causes are mainly:[2]

Overall, secondary causes are more common than primary ones.[2]

Thymic versus peripheral

Causes of T cell deficiency by thymic hypoplasia 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)

Effects

Pathogens of concern

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

Other intracellular pathogens of major concern in T cell deficiency are:

Presentations

Presentations differ among causes, but T cell insufficiency generally manifests as unusually severe common viral infections (e.g. by respiratory syncytial virus (RSV), enterovirus, rotavirus), mucocutaneous candidiasis, diarrhea, and eczematous or erythrodermatous rashes.[1] Failure to thrive and cachexia are late signs of a T-cell defect.[1]

References

  1. 1.0 1.1 1.2 1.3 1.4 Medscape > T-cell Disorders. Author: Robert A Schwartz, MD, MPH; Chief Editor: Harumi Jyonouchi, MD. Updated: May 16, 2011
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Page 432, Chapter 22, Table 22.1 in: Lua error in package.lua at line 80: module 'strict' not found.
  3. 3.0 3.1 Page 435 in: Lua error in package.lua at line 80: module 'strict' not found.