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Interleukin-2 Soluble Receptor α

CPT: 83520
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  • IL-2 sRα

Expected Turnaround Time

3 - 6 days

Related Documents

Specimen Requirements


Serum, frozen


0.5 mL

Minimum Volume

0.3 mL (Note: This volume does not allow for repeat testing.)


Red-top tube or gel-barrier tube


Transfer the serum into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen specimens, please submit frozen specimens for each test requested.

Storage Instructions


Stability Requirements




14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Thawed specimen

Test Details


Serum soluble Interleukin-2-receptor (sIL-2r) is an important disease marker in hemophagocytic lymphohistiocytosis (HLH).


Results of this test are labeled for research purposes only by the assay's manufacturer. The performance characteristics of this assay have not been established by the manufacturer. The result should not be used for treatment or for diagnostic purposes without confirmation of the diagnosis by another medically established diagnostic product or procedure. The performance characteristics were determined by Labcorp.


Immunochemiluminometric assay (ICMA)

Reference Interval

223−710 units/mL

Additional Information

The interleukin-2 (IL-2) receptor complex is an αβγ trimer, in which all three chains are in contact with the ligand. The α subunit of this complex, IL-2Rα (also known at Tac antigen and a CD25) is a 55-kilodalton transmembrane glycoprotein with only 13 amino acids of 351 located on the cytoplasmic side of the membrane.1,2 A soluble form of IL-2Rα appears in serum, concomitant with its increased expression on cells.3 Increased levels of the soluble IL-2Rα in biological fluids correlate with activation of T and/or B cells.3 Results of a number of studies suggest a correlation of levels of IL-2Rα in serum with disease activity in autoimmune and infectious disorders as well as in transplantation rejection.3-5 Markedly increased IL-2sRα levels have been associated with hematologic malignancies.3-5 Levels of IL-2Rα correlate with tumor burden and response to therapy in numerous malignancies.3-7 IL-2Rα levels can be used to predict the long-term prognosis in non-Hodgkin lymphoma patients and to assess the status of patients with HIV and acquired immunodeficiency.3


1. Smith KA. The interleukin 2 receptor. Annu Rev Cell Biol. 1989;5:397-425 (review).2688708
2. Nelson BH, Willerford DM. Biology of interleukin-2 receptor. Adv Immunol. 1998;70:1-81 (review).9755337
3. Rubin LA, Nelson DL. The soluble interleukin-2 receptor: Biology, function, and clinical application. Ann Intern Med. 1990 Oct 15;113(8):619-627 (review).2205142
4. Chrobák L. Clinical significance of soluble interleukin-2 receptor. Acta Medica (Hradec Kralove). 1996;39(1):3-6 (review).9106384
5. Zerler B. The soluble interleukin-2 receptor as a marker for human neoplasia and immune status. Cancer Cells. 1991 Dec;3(12):471-479.1820093
6. Bodey B, Psenko V, Lipsey AL, Kaiser HE. Soluble interleukin-2 receptors in sera of children with primary malignant neoplasms. Anticancer Res. 1996 Jan-Feb;16(1):219-224.8615612
7. Wagstaff J, Baars JW, Wolbink GJ, Hoekman K, Eerenberg-Belmer AJ, Hack CE. Renal cell carcinoma and interleukin-2: A review. Eur J Cancer. 1995;31A(3):401-408 (review).7540404


Hayden A, Lin M, Park S, et al. Soluble interleukin-2 is a receptor is a sensitive diagnostic test in adult HLH. Blood Adv. 2017 Dec 6;1(26):2529-2534.29296904
Henter JI, Horne A, Aricó M, et al. HLH-2004: Diagnostic and therapeutic guidelines for hemophagocytic lymphohistiocytosis. Pediatr Blood Cancer. 2007 Feb;48(2):124-131.16937360


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
142455 IL-2 Receptor Alpha 44422-4 142457 IL-2 Receptor Alpha U/mL 44422-4

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