Soluble IL 2 Receptor (Sendout)

Test Utility: This test is ordered as part of the workup for hyperinflammatory syndromes such as hemophagocytic lymphohistiocytosis (HLH). This test should be ordered concurrently or after Hyperinflammatory Screening Labs have been obtained (CBC with diff, ferritin, fibrinogen, triglycerides, LDH, and D-dimer).

The following are consistent with, but not specific for, a diagnosis of HLH:

-Elevated sIL-2R, CXCL-9, and IL-18
-Elevated sCD163
-Reduced NK function (or cell surface expression of CD107alpha)
-Reduced perforin, SAP, or XIAP

Test Information: The soluble interleukin-2 receptor level is measured by a solid-phase, two-site chemiluminescent immunometric assay. A luminometer reads the light produced, converts it to counts per second, and, using the standard curve recorded in the machine, converts to units per mL (U/mL). Basiliximab binds with the IL-2R in vivo. Results for patients on basiliximab reflect the unbound portion of sIL2R in the plasma sample.

Ordering Requirements: Submit orders via Epic. A completed Cincinnati Children's Hospital requisition is not required.

Reference Interval:

Outside Laboratories: Centrifuge sample and transfer plasma to a separate plastic aliquot. Freeze plasma at immediately at -20°C while awaiting shipment. Transport on dry ice.

• Note: Plasma must be separated from cells within 24 hours of collection.

Stability: Frozen (required): 6 months; Ambient: Unacceptable; Refrigerated: Unacceptable.

Centrifuge sample and transfer plasma to a separate vial; freeze immediately at -20°C.

• Note: Plasma must be separated from cells within 24 hours of collection.

Sendouts:

• Order Cincinnati Children's Test: 2904000.
• Complete a Cincinnati Children's Diagnostic Immunology Laboratory Requisition.
• Ship FedEx Priority Overnight, Monday through Thursday only, with sufficient dry ice to ensure that samples remain frozen throughout transport.
  • Package samples as close to FedEx pickup as possible to ensure that samples remain frozen upon arrival at Cincinnati Lab.
  • Samples that arrive thawed will be rejected.
  • Saturday delivery is not available for this laboratory.

Stability: Frozen (required): 6 months; Refrigerated: Unacceptable; Ambient: Unacceptable.

Reject Due To: Whole blood sent frozen or 24 hours past stability, blood collected in wrong container/tube type, separated plasma/serum sent room temperature or refrigerated.