Lab Test

Interleukin 2, Serum

IL2, IL-2, T-Cell Growth Factor, (TCGF), Thymocyte Stimulation Factor, (TSF), Thymocyte Mitogenesis Factor, (TMF), T-Cell Replacing Factor, (TRF), Killer Helper Factor, (KHF), Interleukin 2 by MAFD, Interleukin-2

Test Codes

ARUP #51588, Antrim #81210, EPIC: LAB7072, SOFT: XINT2

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube.
Also acceptable: One plain Red-top tube.

  • Critical frozen. Send specimens for processing immediately after collection.
  • Separate samples must be submitted when multiple tests are ordered.

Physician Office/Draw Specimen Preparation

Critical frozen. Centrifuge to separate serum cells within two hours of collection. Transfer serum into a plastic transport tube and freeze (-20°C/-4°F or below) immediately.

Preparation for Courier Transport

Transport: 1.0 mL serum, frozen (-20°C/-4°F or below). (Minimum: 0.4 mL)

Rejection Criteria

Specimens not collected and processed as indicated.

Inpatient Specimen Preparation

Critical frozen. Deliver specimen to the Laboratory immediately for processing.

In-Lab Processing

Critical frozen. Centrifuge to separate serum from cells within two hours of collection. Transfer serum into a plastic transport tube and freeze (-20°C/-4°F or below) immediately.

Transport: 1.0 mL serum, frozen (-20°C/-4°F or below). (Minimum: 0.4 mL) 


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 30 minutes
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): 1 year

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.


Sent to ARUP Laboratories, Salt Lake City, UT.


Sunday – Saturday.
Results available in 2-5 days.

Reference Range

Less than or equal to 2.1 pg/mL.

Test Methodology

Quantitative Multiplex Bead Assay.


Interleukin 2 (IL-2) is a glycoprotein produced by activated T-cells that has a variety of immunologic functions, the most notable being the ability to promote the proliferation and maturation of activated T-cells. IL-2 has been known by various names, including T-Cell Growth Factor (TCGF), Thymocyte Stimulation Factor (TSF), Thymocyte Mitogenesis Factor (TMF), T-Cell Replacing Factor (TRF), and Killer Helper Factor (KHF).

Clinical Utility

Decreased production of this cytokine has been associated with the following disease states: systemic lupus erythematosus (SLE), Hodgkin's disease, lepromatous leprosy and AIDS. The ability of IL-2 to stimulate killer cells and enhance their cytotoxicity has led to the combined usage of IL-2 and lymphocyte activated killer cells (LAK) for the treatment of certain cancers.

Cytokine levels may demonstrate diurnal variation. For longitudinal comparison, it is recommended that cytokine levels be determined at the same time of day.

CPT Codes



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This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.