Paraneoplastic Autoantibody Evaluation, Serum
Method Description Describes how the test is performed and provides a method-specific reference
Indirect Immunofluorescence Assay (IFA):
Before screening for neuronal nuclear and cytoplasmic autoantibodies, patient's serum is preabsorbed with liver tissue extract to remove nonorgan-specific autoantibodies. After application to a composite substrate of frozen mouse tissues (brain, kidney, and gut), washing, fluorescein-conjugated goat antihuman IgG is applied to detect the distribution and pattern of the patient's bound IgG.(Vernino S, Lennon VA: New Purkinje cell antibody [PCA 2]: marker of lung cancer related neurological autoimmunity. Ann Neurol 2000;47:297-305;Lennon VA: The case for a descriptive generic nomenclature: classification of immunostaining criteria for PCA-1, ANNA-1, and ANNA-2 autoantibodies. Neurology 1994;44:2412-2415; Chan KH, Vernino S, Lennon VA: ANNA-3 anti-neuronal nuclear antibody: marker of lung cancer-related autoimmunity. Ann Neurol 2001 September;50:301-311; Yu Z, Kryzer TJ, Griesmann GE, et al: CRMP-5 neuronal autoantibody: marker of lung cancer and thymoma-related autoimmunity. Ann Neurol 2001 February;49:146-154)
Goat antihuman IgG and IgM is used as precipitant in all assays. 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. (125)I recombinant human GAD65 is used as antigen to confirm GAD65 autoantibody (when suspected from immunofuorescent 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 December;73:1161-1166)
Acetylcholine receptor modulating antibodies (muscle AChR) 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 then 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 IFA screening 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 (5% for PCA-2 and ANNA-3). Full-length recombinant human CRMP-5 antigen is used to confirm CRMP-5-IgG. Denatured full-length recombinant human amphiphysin protein is used to confirm Amphiphysin Antibody.(Yu Z, Kryzer TJ, Griesmann GE, et al: CRMP-5 neuronal autoantibody: marker of lung cancer and thymoma-related autoimmunity. Ann Neurol 2001 February;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, ANNA-2, ANNA-3, AGNA-1, PCA-1, PCA-2, PCA-Tr, Amphiphysin, CRMP-5-IgG, striational antibodies: Monday through Thursday, Sunday; 10:30 p.m.
P/Q-type calcium channel antibody, N-type calcium channel antibody: Monday, Wednesday, Friday; 6 a.m.
ACh receptor (muscle) binding antibody: Monday through Thursday; 6 p.m., Saturday; 10 a.m.
AChR ganglionic neuronal antibody, neuronal (V-G) K+ channel autoantibody: Tuesday, Thursday, Sunday; 6 a.m.
Paraneoplastic autoantibody Western blot: Monday, Wednesday, Friday; 6 a.m.
CRMP-5-IgG Western blot: Monday through Friday; 6 a.m.
Amphiphysin Western blot: Tuesday, Thursday; 6 a.m.
GAD65 antibody assay: Monday through Thursday, Sunday; 8 a.m.
ACh receptor (muscle) modulating antibodies: Monday through Thursday; 11 a.m.
NMO/AQP4-IgG CBA: Monday through Friday; 8 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.
10 days (negative)
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
17 days (confirmatory testing)
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