Test Information

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Natural Killer Cell Function Assay

Test Code: 30035

Cpt Code:

86849 (x1)

Clinical Utility

This assay evaluates the functional capacity of natural killer (NK) cells. NK cells mediate killing of virally infected cells and tumor cells. Decreased natural killer cell function has been observed in patients with recurrent viral infections and cancer patients.


PBMCs are isolated from whole blood. Isolated PBMCs are mixed at various ratios with fluorescently labeled K562 target cells. Following an incubation period, the percent lysed K562 cells at each concentration are determined by flow cytometry.

Assay Range

The LU10 value is the number of lytic sets contained within a population of 10 million lymphocytes. One lytic set is the number of lymphocytes required to lyse 10 percent of target cells. The reference range is 5.8-59.2 LU10. The reference interval is the central 95th percentile of range from a healthy adult population.

Causes For Rejection

Specimen greater than 23 hours old, tubes less than half full, hemolyzed samples, samples received ambient, anticoagulant other than ACD

Turnaround Time

2-3 days from receipt of specimen (business days)


Ship on cold packs, priority overnight

Specimen Information

whole blood -12 mL of whole blood should be collected in a ACD tube. Blood must be drawn Monday - Thursday 11:00 AM - 5:00 PM Central Time and shipped with cold packs priority overnight on the same day as collection to to meet the 23 hour requirement.


Specimens are approved for testing in New York only when indicated in the Specimen Information field above.

The CPT codes provided are based on Viracor-IBT's interpretation of the American Medical Association's Current Procedural Terminology (CPT) codes and are provided for general informational purposes only. CPT coding is the sole responsibility of the billing party. Questions regarding coding should be addressed to your local Medicare carrier. Viracor-IBT assumes no responsibility for billing errors due to reliance on the CPT codes illustrated in this material.



1. Orange JS. Human natural killer cell deficiencies. Curr Opin Allergy Clin Immunol. 2006 Dec;6(6):399-409.

2. Waldhauer I, Steinle A. NK cells and cancer immunosurveillance. Oncogene. 2008 Oct 6;27(45):5932-43.

3. Strowig T, Brilot F, Münz C. Noncytotoxic Functions of NK Cells: Direct Pathogen Restriction and Assistance to Adaptive Immunity. J Immunol. 2008 Jun 15;180(12):7785-91.

4. Cheent K, Khakoo Sl. Natural killer cells: integrating diversity with function. Immunology. 2009 Apr;126(4):449-57.

5. Etzioni A, Eidenschenk C, Katz R, et al. Fatal varicella associated with selective natural killer cell deficiency. J Pediatri. 2005 Mar;146(3):423-5.

6. Beano A, Signorino E, Evangelista A, et al. Correlation between NK function and response to trastuzumab in metastatic breast cancer patients. J Transl Med. 2008 May 16;6-25.

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