Neuromyelitis Optica (NMO) Evaluation with Reflex, Serum
Method Description Describes how the test is performed and provides a method-specific reference
NMO/AQP4-IgG Enzyme-Linked Immunosorbent Assay:
A 50 microL aliquot of undiluted serum, is added to AQP4 coated plate wells in duplicate. Then, 25 microL of AQP4-biotin is added to each well. Plates are incubated with shaking for 2 hours at ambient temperature. After aspiration and wash, 100-microL Streptavidin-peroxidase is added to each well. Plates are incubated further with shaking for 20 minutes at ambient temperature. After aspiration and wash, 100-microL peroxidase substrate (tetramethylbenzidine) is added. Plates are further incubated (in the dark) for 20 minutes at ambient temperature. At that time, 50 microL of Stop Solution (0.5 mol/L H2S04) is added to each well. Absorbance is measured at 450nm. (McKeon A, Chen S, Pittock SJ, et al: Comparison of optimized immunohistochemical assay with a novel aquaporin-4-specific ELISA for detection of NMO-IgG. Ann Neurol 2009;66:S37).
The substrate is a frozen composite block of mouse kidney, gut, and cerebellum. Bound IgG is detected by a fluorescein-conjugated goat IgG reactive with human IgG. To eliminate staining by nonorgan-specific IgG, each serum is preabsorbed at 1:60 dilution with liver powder. Results are reported as positive or negative. (Lennon VA, Wingerchuk DM, Kryzer TJ, et al: A serum autoantibody marker of neuromyelitis optica: distinction from multiple sclerosis. Lancet 2004;364:2106-2112)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 9 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
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 The location of the laboratory that performs the test