Autoimmune Dysautonomia Evaluation, Serum
Method Description Describes how the test is performed and provides a method-specific reference
Indirect Immunofluorescence Assay (IFA):
Before testing, patient's serum is preabsorbed with liver powder to remove nonorgan-specific autoantibodies. After applying to a composite substrate of frozen mouse tissues (brain, kidney, and gut) and washing, fluorescein-conjugated goat antihuman IgG is applied to detect the distribution and pattern of patient IgG binding.(Pittock SJ, Kryzer TJ, Lennon VA: Paraneoplastic antibodies coexist and predict cancer, not neurological syndrome. Ann Neurol 2004;56:715-719)
Goat antihuman IgG and IgM is used as precipitant in all assays. Cation channel protein antigens are solubilized from neuronal or muscle membrane, in nonionic detergent, and complexed with a selective high-affinity ligand labeled with iodine.(I) I-labelled recombinant human glutamic acid decarboxylase (GAD65) antigen is used to confirm GAD65 autoantibody (when suspected from immunofluorescent staining pattern).(Griesmann GE, Kryzer TJ, Lennon VA: Autoantibody profiles of myasthenia gravis and Lambert-Eaton myasthenic syndrome. In Manual of Clinical and Laboratory Immunology, Sixth edition. Edited by NR Rose, RG Hamilton, et al. Washington, DC, ASM Press, 2002, pp 1005-1012; Walikonis JE, Lennon VA: Radioimmunoassay for glutamic acid decarboxylase [GAD65] autoantibodies as a diagnostic aid for stiff-man syndrome and a correlate of susceptibility to type 1 diabetes mellitus. Mayo Clin Proc 1998;73:1161-1166)
Muscle acetylcholine receptor (AChR) modulating antibodies are detected by incubating the patient's serum for 14 hours with viable, noninnervated, monolayer cultures of human muscle cells. Percent loss of surface AChR is quantitated by probing with (125)I-alpha-bungarotoxin.(Howard FM Jr, Lennon VA, Finley J, et al: Clinical correlations of antibodies that bind, block, or modulate human acetylcholine receptors in myasthenia gravis. Ann NY Acad Sci 1987;505:526-538)
Enzyme Immunoassay (EIA):
A mixture of sarcomeric proteins extracted from innervated rat skeletal muscle is used as antigen to detect striational antibodies (IgG, IgM, and IgA).(Cikes N, Momoi MY, Williams CL, et al: Striational autoantibodies: quantitative detection by enzyme immunoassay in myasthenia gravis, thymoma, and recipients of D-penicillamine or allogeneic bone marrow. Mayo Clin Proc 1988;63:474-481)
Western Blot (WB):
WB is performed when immunofluorescence assay screening for antineuronal nuclear antibody-type 1 is not interpretable due to interfering autoantibodies. A mixture of neuronal antigens extracted aqueously from adult rat cerebellum is denatured, reduced, and separated by electrophoresis on 10% polyacrylamide gel. Full-length recombinant human CRMP-5 antigen is used to confirm CRMP-5-IgG.(Yu Z, Kryzer TJ, Griesmann GE, et al: CRMP-5 neuronal autoantibody: marker of lung cancer and thymoma-related autoimmunity. Ann Neurol 2001;49:145-154)
Cell Binding Assay (CBA):
Patient serum is applied to a composite slide containing HEK293 cells: 1) Transfected with AQP4 (M1 isoform), 2) Nontransfected. After incubation and washing, fluorescein-conjugated goat IgG reactive with human IgG is applied to detect bound patient IgG.(Lennon VA, Kryzer TJ, Pittock SJ, et al: IgG marker of optic-spinal multiple sclerosis binds to the aquaporin-4 water channel. J Exp Med 2005;202:473-477)
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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.
ANNA-1, ANN2S, ANN3S, PCABP, PCAB2, PCATR, AMPHS, CRMS, AGN1S, NMDIS, AMPIS, GABIS: Monday through Thursday, Sunday; 12 p.m. and 5 p.m.
Striational (striated muscle) antibodies: Monday through Friday; 2 p.m.
N-type calcium channel antibody: Monday through Friday; 6 a.m.
Acetylcholine receptor (muscle AChR) binding antibody: Monday through Friday, Sunday; 2 p.m.
Ganglionic acetylcholine receptor (alpha3) autoantibody: Monday through Thursday, Sunday; 10 p.m.
Neuronal (VGKC) autoantibody: Monday through Thursday, Sunday; 10 p.m.
GAD65 antibody assay: Monday through Friday; 2 a.m.
P/Q-type calcium channel antibody: Monday through Friday; 6 a.m.
Paraneoplastic autoantibody Western blot: Monday through Friday; 8 a.m.
Acetylcholine receptor (muscle) modulating antibodies: Monday through Thursday, Saturday; 12 p.m.
CRMP-5-IgG Western blot: Monday through Friday; 8 a.m.
Amphiphysin Western blot: Monday through Friday; 8 a.m.
NMO/AQP4-IgG CBA, NMDCS, AMPCS, GABCS: Monday through Friday; 4 a.m.