Time Sensitive

Ordering Recommendation

May be useful when evaluating patients for a rare primary immune deficiency called IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X-linked), graft-vs-host disease in post-hematopoietic stem cell transplantation, some malignancies, or autoimmune diseases.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Lavender (K2EDTA) or Pink (K2EDTA).

Specimen Preparation

Transport 4 mL whole blood. (Min: 1 mL) Specimens must be analyzed within 48 hours of collection.

Storage/Transport Temperature


Unacceptable Conditions

Clotted or hemolyzed specimens.


Ambient: Unacceptable; Refrigerated: 48 hours; Frozen: Unacceptable


Quantitative Flow Cytometry




1-3 days

Reference Interval

Test Number
Reference Interval
  TREGS CD4+CD25+FoxP3+CD127- %
Age Reference Interval
Adults 19 & older 1.0-7.0 percent of CD4

  TREGS CD4+CD25+FoxP3+CD127-
Reference Interval
Adults 19 & older 8-48 cells/uL

Interpretive Data

Regulatory T cells (Tregs) suppress the immune response, predominately through the transcription factor FOXP3.  The major Treg population is CD4+, CD25+, CD127- with expression of intracellular FOXP3. Decreased Tregs occur in autoimmune disorders including allergy and asthma.  Low numbers or compromised function of Tregs are found in graft vs host disease following bone marrow transplantation. Increasing Tregs is a potential cell therapy and decreasing Tregs may enhance immune surveillance of cancer cells. Monitoring Tregs may reflect the mechanism of disease and can assess the efficacy of treatment.

Severe FOXP3 compromise identified by low or absent Tregs is characteristic of the IPEX syndrome, which stands for immune dysregulation, polyendocrinopathy, enteropathy, and X-linked syndrome; however, some FOXP3 mutations may completely inhibit function yet still allow detection of the intracellular protein by immunologic methods, so absent Tregs by flow cytometry is sufficient, but not necessary for diagnosis.

Please note, reference intervals were established using normal adult donors aged 19 years and older. Therefore, clinical correlation of the results in pediatric patients is recommended.

Compliance Category

Laboratory Developed Test (LDT)


Pediatric ranges were not established.

Hotline History


CPT Codes

86356 x4


Component Test Code* Component Chart Name LOINC
3002250 TREGS CD4+CD25+FoxP3+CD127- %
3002251 TREGS CD4+CD25+FoxP3+CD127-
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


Regulatory T-Cell Panel, FOXP3