Test Id : QNKS
Natural Killer (NK)/Natural Killer T-Cell Subsets, Quantitative, Blood
Useful For
Suggests clinical disorders or settings where the test may be helpful
Quantitation of the major natural killer (NK)-cell subsets relative to total NK cells (NK cell subsets) or total lymphocytes (NK T cells)
Assessment in the following clinical contexts: HIV, primary immune deficiencies with NK cell defects, NK-cell lymphocytosis, solid-organ transplantation, immune reconstitution following bone marrow or hematopoietic cell transplantation
This test is not useful for diagnosis or classification of NK cell malignancies.
This test should not be used for assessing NK cell cytotoxic function.
Method Name
A short description of the method used to perform the test
Flow Cytometry
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Natural Killer Cell Subset Phenotyping
Natural killer (NK) cell quantitation
NK cell Phenotyping
Cytokine-producing NK cells
Cytotoxic NK cells
NKT cells
Invariant NKT cells
CD56+++ NK cells
CD56 bright NK cells
CD16-positive NK cells
Hemophagocytic lymphohistiocytosis
HLH
NK cell deficiencies
Absolute NK cell defects
Classic NK cell deficiency
NK cells
Specimen Type
Describes the specimen type validated for testing
WB Sodium Heparin
Ordering Guidance
This assay does not measure cell-surface or intracellular proteins on natural killer or natural killer T-cell subsets.
A minimum CD45 lymph count (as measured by flow cytometry in the laboratory) is required to report this test. If that requirement is not met (eg, patients with severe lymphopenia), the test will be canceled and an alternate test will be suggested (TBBS / Quantitative Lymphocyte Subsets: T, B, and Natural Killer [NK] Cells, Blood).
Shipping Instructions
Send specimen Monday through Thursday only. Specimen must arrive within 24 hours of collection and by 10 a.m. Central time on Friday.
Collect and package specimen as close to shipping time as possible. Ship specimen overnight.
Necessary Information
The ordering healthcare professional's name and phone number are required.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Container/Tube: Green top (sodium heparin)
Specimen Volume: 3 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
Additional Information: For serial monitoring, it is recommended that specimens are collected at the same time of day.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
0.2 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
| Gross lipemia | OK |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| WB Sodium Heparin | Ambient | 30 hours | GREEN TOP/HEP |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Quantitation of the major natural killer (NK)-cell subsets relative to total NK cells (NK cell subsets) or total lymphocytes (NK T cells)
Assessment in the following clinical contexts: HIV, primary immune deficiencies with NK cell defects, NK-cell lymphocytosis, solid-organ transplantation, immune reconstitution following bone marrow or hematopoietic cell transplantation
This test is not useful for diagnosis or classification of NK cell malignancies.
This test should not be used for assessing NK cell cytotoxic function.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Natural killer (NK) cells are derived from pluripotent hematopoietic stem cell precursors but develop independently of the thymus. They comprise a key lymphocyte subset (approximately 10%-15% of peripheral blood mononuclear cells) and are a constituent of the innate immune system since these cells do not rearrange their germline DNA to obtain specificity. NK cells serve an important role in host defense against viral infections, as well as tumor surveillance. They are also a component of the adaptive immune response through cytokine production. NK cell functions are governed by a balance between activating receptors and inhibitory receptors.
NK cells are identified by expression of different cell-surface receptors, and they are not a homogeneous population.(1) In general, the most common combination of surface markers used to identify the majority of NK cells is the absence of CD3 (CD3-), along with expression of CD56 (neural cell adhesion molecule) and CD16 (low-affinity IgG Fc receptor-Fc gamma RIII). However, not all NK cells express the CD56 and CD16 markers uniformly and, therefore, can be divided into subsets based on expression of these 2 molecules.(2) The CD16+ CD56+/- (dim or negative) that are CD3- are referred to as cytotoxic NK cells, while the CD56+ (bright) CD16- NK cells are called regulatory or cytokine secreting NK cells.(3) These are not only phenotypically and functionally distinct subsets but also developmentally separate. The majority of human NK cells (approximately 90%) have dim expression of CD56 and moderate to high levels of CD16, as well as perforin and granzymes (2 proteins mediating cytolytic activity) and are therefore high in cytotoxic capability. The remaining minority (approximately 10%) of NK cells are the CD56(bright) cytokine-producing NK cells. Therefore, cytotoxicity and cytokine production are the major functions of NK cells. Cytotoxicity can be subdivided into natural cytotoxicity directed largely toward virally infected cells or tumor cells, in the absence of prior stimulation or immunization, and antibody-dependent cellular cytotoxicity (ADCC) directed against antibody-coated target cells.(4) Circulating NK cells are enriched for the CD56(dim) phenotype, while within the lymph nodes, NK cells are largely CD56(bright). This differential localization is related to the pattern of homing receptors expressed on NK cells: CD56(dim) NK cells express homing markers for inflamed peripheral sites, while CD56(bright) NK cells express receptors for secondary lymphoid organs. The majority of circulating human NK cells, which have cytotoxic function and phenotype (CD56[dim]), are CD27-, while the CD56(bright) cells are CD27+. Therefore, the absence of CD27 expression identifies cytotoxic effector cells within the mature NK cell subsets.(5)
Natural killer T (NKT) cells represent a specialized T-cell population that is distinct from conventional T cells. They express an invariant T-cell receptor (TCR) that recognizes self and bacterial glycosphingolipid antigens presented by the MHC class I-like molecule, CD1d.(11) The development of NKT cells is also unique from regular T cells, as NKT cell precursors are positively selected by CD4+CD8+ cortical thymocytes and the signaling pathways differ from the conventional T cells. Activated NKT cells rapidly produce large amounts of Th1 and Th2 cytokines that transactivate other immune components and, therefore, NKT cells are involved in both innate and adaptive immune responses.(11)
NK cell deficiencies can be present as part of a larger immunological syndrome or as an isolated deficiency. Some of the primary (monogenic) immunodeficiencies that affect NK cell function or numbers include autoimmune lymphoproliferative syndrome (ALPS) related to CASP8 (caspase 8 variants); familial hemophagocytic lymphohistiocytosis (FHL) types 2, 3, and 4 due to variants in the PFP1 (encoding perforin), UNC13D (encoding the Munc13-4 protein) and STX-11 (encoding syntaxin -11), respectively; Hermansky-Pudlak syndrome (AP3B1); Papillon-Lefevre syndrome (CTSC: cathepsin C); nuclear factor kappa-beta essential modulator deficiency (NEMO) due to variants in the IKBKG gene; severe combined immunodeficiencies due to mutations in the IL-2RG, JAK3, ADA, PNP, ADK2 genes; bare lymphocyte syndrome (TAP2 gene); X-linked inhibitor of apoptosis protein deficiency (XIAP gene); X-linked lymphoproliferative disease (XLP): XLP-1 (due to variants in the SAP gene); Griscelli syndrome (RAB27A gene); Chediak-Higashi syndrome (LYST gene); and Wiskott-Aldrich syndrome (WAS gene).(12) Patients with X-linked inhibitor of apoptosis protein (XIAP) deficiency have been variably reported as having either normal numbers of NKT cells (13) or low numbers of NKT cells.(14) The apparent discrepancy in the numbers of NKT cells is likely related to the difference in size of the sample control groups and disease stage of patients between the 2 reports. At the present time, the role of XIAP in development of NKT cells has not been clearly delineated.
The isolated NK-cell deficiencies include the absolute NK-cell deficiency (ANKD), the classic NK-cell deficiency (CNKD), and the functional NK-cell deficiency (FNKD). NK-cell function is absent in ANKD and CNKD and deficient in FNKD, while NK cells are present in the latter but absent in the former 2 conditions. NKT cells are absent only in ANKD and present in both CNKD and FNKD.(12) NK-cell dysfunction has also been reported in systemic juvenile rheumatoid arthritis and macrophage activation syndrome.(15) There is also more data emerging on the pathogenic role of NK cells in atopic and autoimmune diseases.(4)
Patients with HIV-1 show a gradual loss of NK cells that correlates with disease progression. There is a selective loss of CD56(dim) NK cells, while the numbers of CD56(bright) NK cells remain the same. There appears to be a defect in differentiation from immature CD56- NK cells to mature CD56(dim) NK cells (16), with an expansion of the former (CD56-CD16+) NK cells in HIV viremic patients.(17) Differential mobilization of NK-cell subsets has also been reported related to acute exercise, with CD56(bright) NK cells being less responsive than CD56(dim) NK cells and the ratio of CD56(bright):CD56(dim) favors the former at least up to 1-hour post-exercise.(18)
NK cells also play an important role in regulating viral infections, and their deficiency predisposes individuals to susceptibility with herpes virus infections. NKG2D expression has been reported to decrease during human cytomegalovirus infection.(19) NK cells that express inhibitory receptors to self-MHC class I molecules are called "licensed," which means they are functionally more responsive to stimulation, while "unlicensed" NK cells lack receptors for self-MHC class I and are hyporesponsive. Contrary to the hypothesis that "licensed" NK cells are key for viral immunity, the depletion of "unlicensed" NK cells impairs control of viremia, suggesting that these cells are critical for protection against viral infection.
NK-cell lymphocytosis is seen in NK-neoplasias, extranodal NK/T-cell lymphoma, aggressive NK-cell leukemia, and blastic NK-cell lymphoma. Chronic NK-cell lymphocytosis is an indolent disorder characterized by proliferation of CD3-CD56+CD16- NK cells. Epstein-Barr virus (EBV) can infect nonneoplastic NK cells(20), and there is an expansion of CD16+CD56(dim) NK cells. Chronic active EBV infection involving NK cells can present with severe inflammatory and necrotic skin reactions typically associated with EBV+ NK-cell lymphoproliferative disease.(21)
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
The appropriate age-related reference values will be provided on the report. Pediatric reference values are not available for patients younger than 7 years and therefore, interpretation will be based on the 7- to 17-year old ranges with appropriate cautionary statements in the interpretation.
Interpretation
Provides information to assist in interpretation of the test results
Interpretive comments will be provided, where applicable, along with reference range values for adult patients and pediatric patients from age 7 to 17 years. Since a separate pediatric reference range could not be established for patients younger than 7 years at this time, interpretation of these samples will be made using the 7- to 17-year old reference range as an approximate guideline.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Results should be interpreted in conjunction with the relevant clinical context and other appropriate immunological analyses.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Fan YY, Yang BY, Wu CY. Phenotypically and functionally distinct subsets of natural killer cells in human PBMCs. Cell Biol Int. 2008;32(2):188-197
2. Cooper MA, Fehniger TA, Caligiuri MA. The biology of human natural killer-cell subsets. Trends Immunol. 2001;22(11):633-640
3. Poli A, Michel T, Theresine M, Andres E, Hentges F, Zimmer J. CD56bright natural killer (NK) cells: an important NK cell subset. Immunology. 2009126(4):458-465. doi:10.1111/j.1365-2567.2008.03027.x
4. von Bubnoff D, Andres E, Hentges F, Bieber T, Michel T, Zimmer Jl. Natural killer cells in atopic and autoimmune diseases of the skin. J Allergy Clin Immunol. 2010;125(1):60-68. doi:10.1016/j.jaci.2009.11.020
5. Vossen MT, Matmati M, Hertoghs KM, et al. CD27 defines phenotypically and functionally different human NK cell subsets. J Immunol. 2008;180(6):3739-3745. doi:10.4049/jimmunol.180.6.3739
6. Suarez-Alvarez B, Lopez-Vazquez A, Baltar JM, Ortega F, Lopez-Larrea C. Potential role of NKG2D and its ligands in organ transplantation: a new target for immunointervention. Am J Transplant. 2009;9(2):251-257. doi:10.1111/j.1600-6143.2008.02526.x
7. Borrego F, Robertson MJ, Ritz J, Pena J, Solana R. CD69 is a stimulatory receptor for NK cell and its cytotoxic effect is blocked by CD94 inhibitory receptor. Immunology. 1999;97(1):159-165. doi:10.1046/j.1365-2567.1999.00738.x
8. Takahashi K, Aranami T, Endoh M, Miyake S, Yamamura T. The regulatory role of natural killer cells in multiple sclerosis. Brain. 2004;127(Pt 9):1917-1927. doi:10.1093/brain/awh219
9. Alter G, Malenfant JM, Altfeld M: CD107a as a functional marker for the identification of natural killer cell activity. J Immunol Methods. 2004;294(1-2):15-22
10. Mathew PA, Chuang SS, Vaidya SV, Kumaresan PR, Boles KS, Pham HTK. The LLT1 receptor induces IFN-gamma production by human natural killer cells. Mol Immunol. 2004;40(16):1157-1163. doi:10.1016/j.molimm.2003.11.024
11. Godfrey DI, Stankovic S, Baxter AG. Raising the NKT cell family. Nat Immunol. 2010;11(3):197-206. doi:10.1038/ni.1841
12. Orange JS. Human natural killer cell deficiencies. Curr Opin Allergy Clin Immunol. 2006;6(6):399-409
13. Marsh RA, Villaneuva J, Kim MO, et al. Patients with X-linked lymphoproliferative disease due to BIRC4 mutation have normal invariant natural killer T-cell populations. Clin Immunol. 2009;132(1):116-123. doi:10.1016/j.clim.2009.03.517
14. Rigaud S, Fondaneche MC, Lambert N, et al. XIAP deficiency in humans causes an X-linked lymphoproliferative syndrome. Nature. 2006;444:110-114. doi:10.1038/nature05257
15. Villanueva J, Lee S, Giannini EH, et al. Natural killer cell dysfunction is a distinguishing feature of systemic onset juvenile rheumatoid arthritis and macrophage activation syndrome. Arthritis Res Ther. 2005;7:R30-R37. doi:10.1186/ar1453
16. Tarazona R, Casado JG, Delarosa O, et al. Selective depletion of CD56(dim) NK cell subsets and maintenance of CD56(bright) NK cells in treatment-naive HIV-1-seropositive individuals. J Clin Immunol. 2002;22(3):176-183. doi:10.1023/a:1015476114409
17. Mavilio D, Lombardo G, Benjamin J, et al. Characterization of CD56-/CD16+ natural killer (NK) cells: a highly dysfunctional NK subset expanded in HIV-infected viremic individuals. Proc Natl Acad Sci USA. 2005;102(8):2886-2891. doi:10.1073/pnas.0409872102
18. Timmons BW, Cieslak T. Human natural killer subsets and acute exercise: a brief review. Exerc Immunol Rev. 2008;14:8-23
19. Muntasell A, Magri G, Pende D, Angulo A, Lopez-Botet M. Inhibition of NKG2D in NK cells by cytokines secreted in response to human cytomegalovirus infection. Blood. 2010;115(25):5170-5179. doi:10.1182/blood-2009-11-256479
20. Trempat P, Tabiasco J, Andre P, et al. Evidence for early infection on nonneoplastic natural killer cells by Epstein-Barr virus. J Virol. 2002;76(21):11139-11142. doi:10.1128/jvi.76.21.11139-11142.2002
21. Pacheco SE, Gottschalk SM, Gresik MV, Dishop MK, Okmaura T, McCormick TG. Chronic active Epstein-Barr virus infection of natural killer cells presenting as severe skin reaction to mosquito bites. J Allergy Clin Immunol. 2005 Aug;116(2):470-472. doi:10.1016/j.jaci.2005.04.044
22. Mace EM, Orange JS. Emerging insights into human health and NK cell biology from the study of NK cell deficiencies. Immunol Rev. 2019;287(1):202-225
23. Delmonte OM, Fleisher TA. Flow cytometry: Surface markers and beyond. J Allergy Clin Immunol. 2019;143(2):528-537
24. Knight V, Heimall JR, Chong H, et al. A toolkit and framework for optimal laboratory evaluation of individuals with suspected primary immunodeficiency. J Allergy Clin Immunol Pract. 2021;9(9):3293-3307.e6
Method Description
Describes how the test is performed and provides a method-specific reference
The absolute quantitation of natural killer (NK) subsets is performed as a 2-tube assay with BD Trucount tubes. Tube 1 provides the isotype control for CD56 and CD16 markers. A combination of antibodies directed against the following surface markers are used to identify the 4 major NK subsets as well as natural killer T cells. Whole blood is stained with the surface marker antibodies in the dark for 20 minutes, followed by red blood cells lysis for 10 minutes in BD FACS Lysing solution. Samples are analyzed on a BD FACS Canto II flow cytometer and data analysis is performed in FACS DIVA 8.0 software.(Unpublished Mayo method)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday through Friday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
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Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
86356 x3
86359
86357
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| QNKS | Quantitative NK/NKT Subsets | 98073-0 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| NKA45 | Total Lymphs (CD45+) | 27071-0 |
| NKP3N | % Total CD45+CD3- cells | 89311-5 |
| NKA3N | Total CD45+CD3- cells | 89313-1 |
| NKP | % Total NK Cells | 8112-5 |
| NKA | Total NK Cells | 9728-7 |
| NKPCY | % Cytotoxic NK (CD16++CD56+) | In Process |
| NKACY | Cytotoxic NK (CD16++CD56+) | 42188-3 |
| NK56P | % Cytokine-Producing NK (CD56++) | 8133-1 |
| NK56A | Cytokine-Producing NK (CD56++) | 14113-5 |
| NKPL3 | % Total CD45+CD3+ Cells | In Process |
| NKAL3 | Total CD45+CD3+ Cells | 89312-3 |
| NKTP | % NKT cells (CD3+CD56+) | 17135-5 |
| NKTA | NKT cells (CD3+CD56+) | 26858-1 |
| QNKSI | Quantitative NK/NKT Interpretation | 69052-9 |