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Test Code NK FUNCT NK Functional Analysis

Important Note

Samples should be drawn Monday - Thursday 10AM - 1330 PM ONLY.

Clinical System Name

NK Functional Analysis


Natural killer (NK) cells are a subset of cytotoxic lymphocytes that have the ability to induce cell death in tumor cells or in virally infected cells.  NK cells play a crucial role in the homeostasis of the immune system. They are typically characterized by the expression of CD16 and CD56 on their cell surface.

Sample Requirements

Specimen: Whole Blood

Container(s): Dark Green Top/Na Heparin

Preferred Vol: See Table Below

Minimum Vol: See Table Below


Notes: Samples should be drawn Monday - Thursday 10AM - 1330 PM ONLY. Send tubes to lab immediately. Whole blood samples MUST reach the reference lab within 24 hours of the blood draw.  Samples drawn outside of these times will be rejected.


Absolute Lymphocyte Count (K/mcL ALC (cells/mcL) mL of Na Heparin blood needed
>1.00 >1000 5.0
1.00 1000 5.0
0.90 900 5.5
0.80 800 6.0
0.70 700 6.5
0.60 600 7.5
0.50 500 9.0
0.40 400 11.0
0.30 300 15.0
0.20 200* 25.0
0.10 100* 45.0
<0.10 <100* 50.0

*For counts below 200 cells/mcL, consider waiting until count increases.

Processing Instructions

Reject due to:

Spin: N

Aliquot: N

Temp: RT

Storage location: Affix large Cerner labels to tubes and place in room temp send-outs rack. Store extra labels in the clear plastic box attached to CPA refrigerator. Alert Send-outs team.


Off-site collection: No off-site collection.


Specimen Type Temperature Time
Whole blood Room temp 24 h



N 3-5 d


Performing Laboratory

Cincinnati Children’s Diagnostic Immunology Laboratories


Department:  Cincinnati Children’s Diagnostic Immunology Laboratories, 3333 Burnet Ave, Cincinnati, OH 45229

Phone Number: (513) 636-4685

Reference Range

Interpretive report is provided.


Method: This assay makes use of the fact that NK cells will lyse the human erythroleukemia cell line, K562, in vitro. K562 cells are loaded with radioactive chromium and incubated with various ratios of a mononuclear cell preparation. Lysis of the K562 targets by NK cells contained in the cell preparation is measured by the amount of chromium released into the supernatant.

Analytical Volume:


CPT Codes

CPT code

Send Out Instructions

Reference Test Name: NK Function
Reference Test Number: None specified.
Instructions: Send FedEX PRIORITY Overnight to Cincinnati Children's at room temperature M - Th. No Sat delivery.