Sorted By Test Name - Mayo Medical Laboratories

NARC
82026
NKCP
28562
Test Performed By: NMS Labs
3701 Welsh Road
P.O. Box 433A
Willow Grove, PA 19090-0437
Narcolepsy-Associated Antigen, HLA-DQB1 Typing, Blood
Clinical Information: Narcolepsy is a neurological condition affecting about 0.02% to 0.16% of
African American, Caucasian, and Japanese individuals. It can be quite disabling because it is
characterized by abnormal rapid eye movement (REM) sleep, cataplexy, hypnagogic hallucinations, and
sleep paralysis. Studies have identified DQB1*06:02 as a useful marker of narcolepsy. While
DQB1*06:02 is found in virtually all African American, Caucasian, and Japanese narcoleptics, it must be
clearly understood that some patients do not have this allele and, more importantly, about 25% of normal
people have this gene. Because DQB1*06:02 is present in the normal population, no test for an HLA gene
constitutes a test for narcolepsy. A more reliable approach would be to consider that, in an appropriate
patient, the absence of the strongly associated DQB1*06:02, provides good evidence that the patient does
not have narcolepsy.
Useful For: Ruling out a diagnosis of narcolepsy
Interpretation: If DQB1*06:02 is not detected, the narcolepsy-associated antigen test result will be
reported as negative for DQB1*06:02. If the allele is detected, the result will be reported as positive for
DQB1*06:02.
Reference Values:
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
Current as of January 4, 2013 7:15 pm CST 800-533-1710 or 507-266-5700 or MayoMedicalLaboratories.com Page 1284