Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

NKCP
28562
An interpretive report will be provided.
Clinical References: 1. Mignot E, Lin X, Arrigoni J, et al: DQB1*0602 and DQB1*0102 (DQ1)
are better markers than DR2 for narcolepsy in Caucasian and Black Americans. Sleep 1994;17:S60-67
2. Chabas D, Taheri S, Renier C, Mignot E: The genetics of narcolepsy. Ann Rev Genomics Hum Genet
2003;4:459-483
Natural Killer (NK) Cytotoxicity Profile
Clinical Information: Natural Killer (NK) Cytotoxicity Profile: Lymphocyte-mediated cytotoxicity
(cell-mediated immunity) includes 3 principal types of lytic activity: antibody-dependent cellular
cytotoxicity, T-lymphocyte major histocompatibility complex (MHC) restricted cytotoxicity, and MHC
unrestricted cytotoxicity. The latter is also called NK cell activity. NK cell activity is mediated by
lymphocytes (primarily CD3- and CD16+ large granular and small granular lymphocytes) that are
constitutively cytocidal when incubated with various tumor-transformed or virus-infected cells. NK
lytic activity is postulated to play a physiologic role in host defense against virus-infected cells and in
immune surveillance against tumors. T- and B-Cell Quantitation by Flow Cytometry: Normal immunity
requires a balance between the activities of various lymphocyte subpopulations with different effector
and regulatory functions. Different immune cells can be characterized by unique surface membrane
antigens described by a cluster of differentiation nomenclature (eg, CD3 is an antigen found on the
surface of T lymphocytes). Abnormalities in the number and percent of T (CD3), T-helper (CD4),
T-suppressor (CD8), B (CD19), and natural killer (CD16+CD56) lymphocytes have been described in a
number of different diseases. In patients who are infected with HIV, the CD4 count is measured for
AIDS diagnosis and for initiation of antiviral therapy. The progressive loss of CD4 T lymphocytes in
patients infected with HIV is associated with increased infections and complications. The Public Health
Service has recommended that all HIV-positive patients be tested every 3 to 6 months for the level of
CD4 T lymphocytes. The absolute counts of lymphocyte subsets are known to be influenced by a
variety of biological factors, including hormones, the environment, and temperature. The studies on
diurnal (circadian) variation in lymphocyte counts have demonstrated progressive increase in CD4
T-cell count throughout the day, while CD8 T cells and CD19+ B cells increase between 8:30 am and
noon, with no change between noon and afternoon. NK cell counts, on the other hand, are constant
throughout the day.(1) Circadian variations in circulating T-cell counts have been shown to be
negatively correlated with plasma cortisol concentration.(2-4) In fact, cortisol and catecholamine
concentrations control distribution and, therefore, numbers of naive versus effector CD4 and CD8 T
cells.(2) It is generally accepted that lower CD4 T-cell counts are seen in the morning compared with
the evening (5), and during summer compared to winter.(6) These data, therefore, indicate that timing
and consistency in timing of blood collection is critical when serially monitoring patients for
lymphocyte subsets.
Useful For: Natural Killer (NK) Cytotoxicity Profile: Assessment of patients with several different
immunodeficiency diseases in which the NK cell activity has been reported to be diminished or absent.
These diseases include: -Reticular dysgenesis -X-linked severe combined immunodeficiency disease
(SCID) caused by mutation of the interleukin (IL)-2 receptor gamma chain -Autosomal recessive SCID
caused by JAK3 mutations, and caused by RAG-1 and RAG-2 mutations (Omenn syndrome)
-Adenosine deaminase deficiency -Purine nucleoside phosphorylase deficiency -Zeta-associated
protein-70 (ZAP-70) tyrosine kinase deficiency -Chediak-Higashi syndrome T- and B-Cell Quantitation
by Flow Cytometry: Monitoring CD4 counts and assessing immune deficiencies
Interpretation: Unmeasurable lytic activity or activity