T Regulatory - FOXP3 (TREG)
Utility: 1) Determine CD4+CD25+CD127dim+FoxP3+ regulatory T cells (Treg) in the periph¬eral blood.
2) Diagnostic screen for the presence of X-linked immunodysregulation, polyendocrinopathy and enteropathy (IPEX) by assessing T regulatory cells.
Specimen: 8 - 15 mL peripheral blood in sodium heparin (green top).
CPT codes: 86359, 86360, 86355, 86357, 88184, 88185 x 6, 88188.
Clinical indication/general description
IPEX is an X-linked recessive disorder causing widespread autoimmune manifestations. Mutations in the forkhead transcription factor FoxP3 are responsible for this disease. FoxP3 is crucial to the development, survival and effector function of regulatory T (Treg) cells, a cell population essential to immune regulation. Treg cells account for approximately 5 to 10 percent of peripheral blood CD4+ T cells. Treg cells also express high levels of CD25, the high affinity binding alpha subunit of the IL-2 receptor, and low levels of CD127, the IL-7 receptor. IPEX-like diseases also can be caused by deficiencies in CD25 or STAT5b, key signal transduction subunits of the IL-2 receptor.
Use of antibodies to CD4, CD25, CD127 and FoxP3 allows for the determination of the percentage of Treg cells in peripheral blood of patients suspected of IPEX or IPEX-like diseases.