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FeedbackSemiquantitative Cell-Based Indirect Fluorescent Antibody/Quantitative Radioimmunoassay/Semiquantitative Enzyme-Linked Immunosorbent Assay
Semiquantitative Cell-Based Indirect Fluorescent Antibody/Quantitative Radioimmunoassay/Semiquantitative Enzyme-Linked Immunosorbent Assay
Autoimmune encephalitis may be suspected in patients with subacute onset of new, unexplained neurologic symptoms. Antibodies associated with autoimmune encephalitis may be present in the serum or cerebrospinal fluid (CSF) and can serve as useful markers of disease.
Disease Overview
Autoimmune encephalitis presents with diverse neurologic phenotypes, including encephalopathy, epilepsy, movement disorders, and psychiatric symptoms, among others. The detection of antineural antibodies may help establish a diagnosis, support treatment decisions, aid prognostication, serve as a prerequisite for enrollment in clinical trials, and guide the search for an associated malignancy. Because the differential diagnosis is broad, choosing a targeted phenotypic panel based on a patient’s predominant clinical features, rather than a broad antibody panel, is often recommended.
For more information about laboratory testing for autoimmune neurologic diseases, including detailed information about panel test selection, refer to the ARUP Consult Autoimmune Neurologic Diseases - Antineural Antibody Testing topic.
Test Description
ARUP’s serum Autoimmune Encephalitis Extended Panel and CSF Autoimmune Encephalitis Reflex Panel can be used to evaluate suspected autoimmune disease of the central nervous system (CNS). Testing for the presence of antineural antibodies in both serum and CSF is recommended in most situations.
These panels do not test for paraneoplastic antibodies. To evaluate for paraneoplastic antibodies, refer to ARUP’s Paraneoplastic Reflexive Panels.
These panels cover a broad range of autoimmune neurologic phenotypes; for greater diagnostic yield and improved turnaround time, consider choosing a phenotype-specific panel (see table below) rather than a broad panel.
| ARUP Panel | Test Code | |
|---|---|---|
| Serum | CSF | |
| Autoimmune Encephalopathy/Dementia Panel | 3006201 | 3006202 |
| Autoimmune Epilepsy Panel | 3006204 | 3006205 |
| Autoimmune Movement Disorder Panel | 3006206 | 3006207 |
| Autoimmune Myelopathy Panel | 3006208 | 3006209 |
| Autoimmune Dysautonomia Panel | 3006203 | — |
| Autoimmune Pediatric CNS Disorders | 3006210 | 3006211 |
Regardless of the panel chosen, order only one panel for serum and/or one panel for CSF; many antineural antibodies are redundant between these panels, and choosing based on the predominant phenotype will provide the most meaningful results. To compare these panels and the antibodies included, refer to ARUP Autoimmune Neurology Panel Components.
Testing for individual autoantibodies is also available separately and can be used for long-term monitoring.
Antibodies Tested and Methodology
| Autoantibody Marker | Method | Individual Autoantibody or Focused Panel Test Code | |
|---|---|---|---|
| Serum | CSF | ||
| AMPAR Ab, IgG | CBA-IFA | 3001260 | 3001257 |
| AQP4 Ab, IgG | CBA-IFA, reflex titer | 2013320 | 2011699 |
| CASPR2 Ab, IgG | CBA-IFA, reflex titer | 2009452 | 3001986 |
| DPPX Ab, IgG | CBA-IFA, reflex titer | 3004359 | 3004512 |
| GABA-AR Ab, IgG | CBA-IFA, reflex titer | 3006008 | 3006003 |
| GABA-BR Ab, IgG | CBA-IFA, reflex titer | 3001270 | 3001267 |
| GAD65 Ab | ELISA | 2001771 | 3002788 |
| IgLON5 Ab, IgG | CBA-IFA, reflex titer | 3006018 | 3006013 |
| LGI1 Ab, IgG | CBA-IFA, reflex titer | 2009456 | 3001992 |
| mGluR1 Ab, IgG | CBA-IFA, reflex titer | 3006044 | 3006039 |
| MOG Ab, IgG | CBA-IFA, reflex titer | 3001277 | — |
| NMDAR Ab, IgG | CBA-IFA, reflex titer | 2004221 | 2005164 |
| VGKC Ab, IgG | RIA | 2004890 | 3001387 |
| Ab, antibody; AMPAR, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor; AQP4, aquaporin-4; CASPR2, contactin-associated protein 2; CBA, cell-binding assay/cell-based assay; DPPX, dipeptidyl-aminopeptidase-like protein 6; ELISA, enzyme-linked immunosorbent assay; GABA-AR, gamma-aminobutyric acid receptor, type A; GABA-BR, gamma-aminobutyric acid receptor, type B; GAD65, glutamic acid decarboxylase 65-kd isoform; IFA, indirect immunofluorescence assay; Ig, immunoglobulin; IgLON5; IgLON family member 5; LGI1, leucine-rich, glioma-inactivated protein 1; mGluR1, metabotropic glutamate receptor 1; MOG, myelin oligodendrocyte glycoprotein; NMDAR, N-methyl-D-aspartate receptor; RIA, radioimmunoassay; VGKC, voltage-gated potassium channel | |||
Reflex Patterns
Autoimmune Encephalitis Extended Panel, Serum (3006050) and Reflex Panel, CSF (3006049): Reflex Patterns
Limitations
These tests do not include all known antineural antibodies:
- Some antibodies are extremely rare or are of uncertain clinical significance.
- As testing for newly described antibodies becomes available and their clinical relevance is established, these panels may evolve to reflect these discoveries.
Test Interpretation
Results
Results must be interpreted in the clinical context of the individual patient; test results (positive or negative) should not supersede clinical judgment.
| Result | Interpretation |
|---|---|
| Positive for ≥1 autoantibodies | Autoantibody(ies) detected May support a diagnosis of autoimmune encephalitis Consider a focused search for malignancy based on antibody-tumor associations |
| Negative | No autoantibodies detected A diagnosis of autoimmune encephalitis is not excluded |
References
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Budhram A, Dubey D, Sechi E, et al. Neural antibody testing in patients with suspected atoimmune encephalitis. Clin Chem. 2020;66(12):1496-1509.
ARUP Autoimmune Neurology Panel Components