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Test Code CD4RT CD4 T-Cell Recent Thymic Emigrants, Blood

Reporting Name

CD4 RTE, Flow Cytometry

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful 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

Method Name

Flow Cytometry


Shipping 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 Type

Whole Blood EDTA

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

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject

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.

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.

Day(s) Performed

Monday through Friday

Report Available

3 to 4 days

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