Unit Code 83380:
Paraneoplastic Autoantibody Evaluation, Serum
Method Description
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[3]: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[2]:146-154)
Radioimmunoassay (RIA)
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. 6th 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[12]: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. (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[2]:145-154)
Performing Laboratory Location
Rochester


