CD4+ T-Cell Recent Thymic Emigrants (RTEs)
Ordering Recommendation
Assess thymic function in suspected severe combined immunodeficiency (SCID), DiGeorge syndrome and other T- cell immune deficiency disorders.
Evaluate immune reconstitution during highly active antiviral therapy (HAART) in HIV patients and post chemotherapy  and hematopoietic cell transplant.
Quantitative Flow Cytometry
1-3 days  
New York DOH Approval Status
Specimens from New York clients will be sent out to a New York DOH approved laboratory, if possible.
Submit With Order
Specimen Required
Patient Preparation
Lavender (EDTA) or green (sodium or lithium heparin).  
Specimen Preparation
Transport 4 mL whole blood. (Min: 0.5 mL)  
Storage/Transport Temperature
Refrigerated. Also acceptable: Room temperature.  
Unacceptable Conditions
Cord blood. Specimens older than 72 hours. Clotted or hemolyzed specimens.  
Specimens must be analyzed within 72 hours of collection.  
Ambient: 72 hours; Refrigerated: 72 hours; Frozen: Unacceptable  
Reference Interval
Test Number Components Reference Interval
 % CD4+CD31+CD45RA+ (RTEs) 
Age Reference Interval
1 Week-​2 months 50-​100% of CD4+
2-​5 months 64-​94% of CD4+
5-​9 months 65-​90 % of CD4+
9-​15 months 61-​93% of CD4+
15-​24 months 40-​100% of CD4+
2-​5 years 37-​100% of CD4+
5-​10 years 41-​81% of CD4+
10-​16 years 31-​81% of CD4+
>16 years 6-​51% of CD4+
 Abs CD4+CD31+CD45RA+ (RTEs) 
Age Reference Interval
1 Week-​2 months 1000-​4900 cells/µL
2-​5 months 1400-​5200 cells/µL
5-​9 months 800-​6200 cells/µL
9-​15 months 900-​5800 cells/µL
15-​24 months 170-​7400 cells/µL
2-​5 years 190-​2600 cells/µL
5-​10 years 200-​1700 cells/µL
10-​16 years 150-​1500 cells/µL
>16 years 51-​609 cells/µL
Interpretive Data
Recent thymic emigrants (RTEs) CD4+CD45RA+CD31+ represent naive T-cells recently migrated from the thymus and are measured as a percent of CD4+ T-cells. A decrease or absence of RTEs is associated with a decrease or loss of thymic output in children, as seen in severe combined immunodeficiency (SCID), DiGeorge syndrome and other cellular immune deficiency disorders. RTE results should be interpreted with caution in adults due to age-related decline in thymic function. RTE assessment may also be used to evaluate immune reconstitution after hematopoietic cell transplant, post chemotherapy and in HIV patients undergoing highly active antiviral therapy (HAART). Serial measurement is recommended.

Compliance Statement A: Analyte specific reagents (ASR) are used in many laboratory tests necessary for standard medical care and generally do not require U.S. Food and Drug Administration (FDA) approval or clearance. This test was developed and its performance characteristics determined by ARUP Laboratories. The U.S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. This test should not be regarded as investigational or for research use.
CPT Code(s)
86356 x3
Component Test Code*Component Chart NameLOINC
2010180% CD4+CD31+CD45RA+ (RTEs) 
2010181Abs CD4+CD31+CD45RA+ (RTEs) 
* 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.