Autoimmune Gastrointestinal Dysmotility Evaluation, Serum
Method Description Describes how the test is performed and provides a method-specific reference
Indirect immunofluorescence assay (IFA):
IFA for neuronal nuclear and cytoplasmic autoantibodies. Patient's serum is preabsorbed with liver powder to remove non-organ-specific autoantibodies before applying a composite substrate of frozen mouse tissues (brain, kidney, and gut). After washing, fluorescein-conjugated goat antihuman IgG is applied to detect the distribution and pattern of the patient's bound IgG.(Pittock SJ, Kryzer TJ, Lennon VA: Paraneoplastic antibodies coexist and predict cancer, not neurological syndrome. Ann Neurol 2004;56:715-719; Yu Z, Kryzer TJ, Griesmann GE, et al: CRMP-5 neuronal autoantibody: marker of lung cancer and thymoma-related autoimmunity. Ann Neurol 2001;49:146-154; Pittock SJ, Yoshikawa H, Ahlskog JE, et al: Glutamic acid decarboxylase autoimmunity with brainstem, extrapyramidal and spinal cord dysfunction. Mayo Clin Proc 2006;81:1207-1214)
Goat antihuman IgG and IgM is used as precipitant in all assays. Iodine-labelled recombinant human glutamic acid decarboxylase (GAD65) is used as antigen to confirm GAD65 autoantibody.(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)
Cation channel protein antigens are solubilized from neuronal or muscle membranes, in non-ionic detergent and complexed with a selective high-affinity ligand that is labeled with (125)I.(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)
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):
The antigen is full-length recombinant human CRMP-5.(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)
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: Monday through Thursday, Sunday; 11:30 a.m.
Striational (striated muscle) antibodies: Monday through Thursday, Sunday; 11 a.m.
N-type calcium channel antibody: Monday, Wednesday, Friday; 2 p.m.
Acetylcholine receptor (muscle AChR) binding antibody: Monday through Thursday, Saturday; 2 p.m.
Ganglionic acetylcholine receptor (alpha3) autoantibody: Tuesday, Thursday, Sunday; 2 p.m.
Neuronal (VGKC) autoantibody: Tuesday, Thursday, Sunday; 2 p.m.
GAD65 antibody assay: Monday through Thursday, Sunday; 6 a.m.
Paraneoplastic autoantibody Western blot: Monday, Wednesday, Friday; 8 a.m.
Acetylcholine receptor (muscle) modulating antibodies: Monday through Thursday; 11 a.m.
CRMP-5-IgG Western blot: Monday through Friday; 8 a.m.
Amphiphysin Western blot: Tuesday, Thursday; 6 a.m.
NMO/AQP4-IgG CBA: Monday through Friday 8:00 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