Sorted By Test Name - Mayo Medical Laboratories

coincides with associated thymic recovery. For patients with DiGeorge syndrome (DGS)-a cellular
immunodeficiency associated with other congenital problems including cardiac defects, facial
dysmorphism, hypoparathyroidism, and secondary hypocalcemia, and chromosome 22q11.2 deletion (in a
significant proportion of patients)-measurement of thymic function provides valuable information on the
functional phenotype, ie, complete DGS (associated with thymic aplasia) or partial DGS (generally
well-preserved thymic function). Thymus transplants have been performed in patients with complete DGS
but are not required in partial DGS.
Useful For: Evaluating thymic reconstitution in patients following hematopoietic stem cell
transplantation, chemotherapy, biological or immunomodulatory therapy, and immunosuppression
Evaluating thymic recovery in HIV-positive patients on highly active antiretroviral therapy (HAART)
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) The CD8 RTE test has limited value in the clinical interpretation
of recent thymic output in adults (see Cautions), and is likely to be of more clinical relevance in pediatric
individuals
Interpretation: The absence or reduction of CD31+CD4 recent thymic emigrants (RTEs) and
CD8+CD103+ RTEs correlates with loss or reduced thymic output and changes in the naive CD4 T-cell
compartment. CD4 RTEs measured along with CD8 RTEs and TREC (TREC/87959 T-Cell Receptor
Excision Circles [TREC] Analysis for Immune Reconstitution) provides a comprehensive assessment of
thymopoiesis. Conversely, increases in CD8 RTEs are of no clinical significance, and do not indicate a
pathologic finding. Since CD8 RTEs is a rare population, small changes in serial measurements may
result in some values being above the reference range; however, as noted, increases in CD8 RTEs do not
have clinical significance. To evaluate immune reconstitution or recovery of thymopoiesis post-T-cell
depletion due to HSCT, immunotherapy, or other clinical conditions, it is essential to serially measure
CD4, CD8 RTE, and TREC levels. A consultative report is provided.
Reference Values:
CD4 T-CELL RECENT THYMIC EMIGRANTS (RTE)
CD4 Absolute
Males
1 month-17 years: 153-1,745 cells/mcL
18-70 years: 290-1,175 cells/mcL
Females
1 month-17 years: 582-1,630 cells/mcL
18-70 years: 457-1,766 cells/mcL
Reference values have not been established for patients that are 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%
56-70 years: 6.4-27.7%
Females
1 month-17 years: 25.8-68.0%
18-25 years: 6.4-51.0%
26-55 years: 6.4-41.7%
56-70 years: 6.4-27.7%
Reference values have not been established for patients that are 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
Females
Current as of January 4, 2013 7:15 pm CST 800-533-1710 or 507-266-5700 or MayoMedicalLaboratories.com Page 1737