An immune system abnormality that involves problems with T-cells caused by a genetic defect.
The list of signs and symptoms mentioned in various sources for T-cell immunodeficiency primary includes the 6 symptoms listed below: * Recurring infections * Increased susceptibility to opportunistic infections * Increased risk of bacterial infections * Increased risk of viral infections * Increased risk of protozoan infections * Increased risk of fungal infections
The basic tests performed when an immunodeficiency is suspected should include a full blood count (including accurate lymphocyte and granulocyte counts) and immunoglobulin levels (the three most important types of antibodies: IgG, IgA and IgM). Other tests are performed depending on the suspected disorder: * Quantification of the different types of mononuclear cells in the blood (i.e. lymphocytes and monocytes): different groups of T lymphocytes (dependent on their cell surface markers, e.g. CD4+, CD8+, CD3+, TCRαβ and TCRγδ), groups of B lymphocytes (CD19, CD20, CD21 and Immunoglobulin), natural killer cells and monocytes (CD15+), as well as activation markers (HLA-DR, CD25, CD80 (B cells). * Tests for T cell function: skin tests for delayed-type hypersensitivity, cell responses to mitogens and allogeneic cells, cytokine production by cells * Tests for B cell function: antibodies to routine immunisations and commonly acquired infections, quantification of IgG subclasses * Tests for phagocyte function: reduction of nitro blue tetrazolium chloride, assays of chemotaxis, bactericidal activity. Due to the rarity of many primary immunodeficiencies, many of the above tests are highly specialised and tend to be performed in research laboratories. Criteria for diagnosis were agreed in 1999. For instance, an antibody deficiency can be diagnosed in the presence of low immunoglobulins, recurrent infections and failure of the development of antibodies on exposure to antigens. The 1999 criteria also distinguish between "definitive", "probable" and "possible" in the diagnosis of primary immunodeficiency. "Definitive" diagnosis is made when it is likely that in 20 years, the patient has a >98% chance of the same diagnosis being made; this level of diagnosis is achievable with the detection of a genetic mutation or very specific circumstantial abnormalities. "Probable" diagnosis is made when no genetic diagnosis can be made, but the patient has all other characteristics of a particular disease; the chance of the same diagnosis being made 20 years later is estimated to be 85-97%. Finally, a "possible" diagnosis is made when the patient has only some of the characteristics of a disease are present, but not all.
The treatment of primary immunodeficiencies depends foremost on the nature of the abnormality. This may range from immunoglobulin replacement therapy intravenous immunoglobulin (IVIG) or subcutaneous immunoglobulin (SCIG) in antibody deficiencies to hematopoietic stem cell transplantation (for SCID). Reduction of exposure to pathogens may be recommended, and in many situations prophylactic antibiotics may be advised