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HelpTest Code CD4RT CD4 T-Cell Recent Thymic Emigrants, Blood
Reporting Name
CD4 RTE, Flow CytometryUseful For
Evaluating thymic reconstitution in patients following hematopoietic cell transplantation, chemotherapy, immunomodulatory therapy, and immunosuppression
Evaluating thymic recovery in patients who are HIV-positive and on highly active antiretroviral therapy
Evaluating thymic output in patients with DiGeorge syndrome or other cellular immunodeficiencies
Assessing the naive T-cell compartment in a variety of immunological contexts (autoimmunity, cancer, immunodeficiency, and transplantation)
Identification of thymic remnants post-thymectomy for malignant thymoma or as an indicator of relapse of disease (malignant thymoma) or other contexts of thymectomy
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Whole Blood EDTAShipping Instructions
Testing is performed Monday through Friday. Specimens not received by 4 p.m. (CST) on Friday may be canceled.
Samples arriving on the weekend and observed holidays may be canceled.
Collect and package specimen as close to shipping time as possible. Ship specimen overnight in an Ambient Shipping Box-Critical Specimens Only (T668) following the instructions in the box.
It is recommended that specimens arrive within 24 hours of collection.
Necessary Information
Ordering healthcare professional name and phone number are required.
Specimen Required
Supplies: Ambient Shipping Box-Critical Specimens Only (T668)
Container/Tube: Lavender top (EDTA)
Specimen Volume: 3 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
Specimen Minimum Volume
1.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole Blood EDTA | Ambient | 48 hours | PURPLE OR PINK TOP/EDTA |
Reference Values
CD4 Absolute
Males
1 month-17 years: 153-1745 cells/mcL
18-70 years: 290-1,175 cells/mcL
Reference values have not been established for patients that are younger than 30 days of age.
Reference values have not been established for patients that are older than 70 years of age.
Females
1 month-17 years: 582-1630 cells/mcL
18-70 years: 457-1,766 cells/mcL
Reference values have not been established for patients that are younger than 30 days of age.
Reference values have not been established for patients that are older than 70 years of age.
CD4 RTE %
Males
1 month-17 years: 19.4-60.9%
18-25 years: 6.4-51.0%
26-55 years: 6.4-41.7%
≥56 years: 6.4-27.7%
Reference values have not been established for patients that are younger than 30 days of age.
Reference values have not been established for patients that are older than 70 years of age.
Females
1 month-17 years: 25.8-68.0%
18-25 years: 6.4-51.0%
26-55 years: 6.4-41.7%
≥56 years: 6.4-27.7%
Reference values have not been established for patients that are younger than 30 days of age.
Reference values have not been established for patients that are older than 70 years of age.
CD4 RTE Absolute
Males
1 month-17 years: 50.0-926.0 cells/mcL
18-70 years: 42.0-399.0 cells/mcL
Reference values have not been established for patients that are younger than 30 days of age.
Reference values have not been established for patients that are older than 70 years of age.
Females
1 month-17 years: 170.0-1007.0 cells/mcL
18-70 years: 42.0-832.0 cells/mcL
Reference values have not been established for patients that are younger than 30 days of age.
Reference values have not been established for patients that are older than 70 years of age.
Day(s) Performed
Monday through Friday
Test Classification
This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
86356
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CD4RT | CD4 RTE, Flow Cytometry | In Process |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 89504 | CD4 Absolute (cells/uL) | 24467-3 |
| 29536 | CD4 RTE % | 8123-2 |
| 29535 | CD4 RTE Absolute | 24467-3 |
| 29178 | Interpretation | 69052-9 |
Interpretation
The absence or reduction of CD31+CD4 recent thymic emigrants (RTE) generally correlates with loss or reduced thymic output and changes in the naive CD4 T-cell compartment, especially in infancy and prepubertal children. The CD4RTE result must be interpreted more cautiously in adults due to age-related decline in thymic function and correlated with total CD4 T cell count and other relevant immunological data. CD4 RTE measured along with TREC (TRECS / T-Cell Receptor Excision Circles Analysis, Blood) provides a comprehensive assessment of thymopoiesis but should not be used in adults over the sixth decade of life as clinically meaningful information on thymic function is limited in the older population due to a physiological decline in thymic activity.
To evaluate immune reconstitution or recovery of thymopoiesis post-T-cell depletion due to post-hematopoietic cell transplant, immunotherapy, or other clinical conditions, it is helpful to systematically (serially) measure CD4RTE and TREC copies in the appropriate age groups.
Clinical Reference
1. Hassan J, Reen DJ. Human recent thymic emigrants-identification, expansion, and survival characteristics. J Immunol. 2001;167(4):1970-1976
2. Kimmig S, Przybylski GK, Schmidt CA, et al. Two subsets of naive T-helper cells with distinct T-cell receptor excision circle content in human adult peripheral blood. J Exp Med. 2002;195(6):789-794
3. Junge S, Kloeckener-Gruissem B, Zufferey R, et al. Correlation between recent thymic emigrants and CD31+ (PECAM-1) CD4 T-cells in normal individuals during aging and in lymphopenic children. Eur J Immunol. 2007;37(11):3270-3280
4. Dong X, Hoeltzle MV, Abraham RS. Evaluation of CD4 and CD8 recent thymic emigrants in healthy adults and children. Unpublished data 2008
5. Duszczyszyn DA, Beck JD, Antel J, et al. Altered naiveCD4 and CD8 T-cell homeostasis in patients with relapsing-remitting multiple sclerosis: thymic versus peripheral (non-thymic) mechanisms. Clin Exp Immunol. 2006;143(2):305-313
6. Nain E, Kiykim A, Ogulur I, et al. Immune system defects in DiGeorge syndrome and association with clinical course. Scand J Immunol. 2019;90(5):e12809. doi:10.1111/sji.12809
Report Available
3 to 4 daysMethod Name
Flow Cytometry
Testing Algorithm
For information see Newborn Screen Follow-up for Severe Combined Immunodeficiency Syndrome (SCID).