INDIVIDUAL TEST 833
LGI-1 Antibodies (IgG)
Indication Suspicion of paraneoplastic syndromes particularly in autoimmune encephalitis.Method Indirect immunofluorescence (IIF) using transfected cells.
Result The result is reported as positive or negative. A positive result is followed by a titer (serum).
Interpretation LGI-1 is a subunit in the potassium channel complex (VGKC). Antibodies against LGI-1 have been reported in classical autoimmune encephalitis and epilepsy. Antibodies against LGI-1 are the second most common in autoimmune encephalitis following antibodies against NMDAR. Antibodies against LG-1 are detected more often in men, age when diagnosed has varied between 30-80 years (median 60 years). LGI-1 antibodies are associated with tumors (lung, thymoma but also other tumor forms) in 25-31% of the cases.
The LGI-1 belongs to the group of extracellular antigens. Generally, immunotherapy is more often effective in autoantibodies directed against extracellular antigens than in autoantibodies against intracellular antigens. Antibody titers can be used to monitor treatment effectiveness. Screening for cancer diagnosis is recommended.
Antibodies against LGI-1 are graded as Lower-risk antibodies with a frequency of <10% of underlying cancer and a positive result yield 0 points PNS score, according to Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
References
- Lai, Huijbers, Lancaster, et al. Investigation of LGI1 as the antigen in limbic encephalitis previously attributed to potassium channels: a case series. Lancet Neurol 2010;9:776-785. PMID 20580615.
- Irani SR, Alexander S, Waters P, et al. Antibodies to Kv1 potassium channelcomplex proteins leucine-rich, glioma inactivated 1 protein and contactin-associated protein-2 in limbic encephalitis, Morvan’s syndrome and acquired neuromyotonia. Brain 2010;133:2734-2748. PMID 20663977.
- Dalmau J, Geis C, Graus F. Autoantibodies to Synaptic Receptors and Neuronal Cell Surface Proteins in Autoimmune Diseases of the Central Nervous System. Physiol Rev. 2017 Apr;97(2):839-887. PMID: 28298428;
- Graus F, et al. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. Neurol Neuroimmunol Neuroinflamm. 2021 May 18;8(4):e1014. PMID: 34006622
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ENSKILD ANALYS 833
LGI-1-antikroppar (IgG)
Indikation Misstanke om paraneoplastiska syndrom och framför allt vid autoimmun encefalit.Metod Indirekt immunofluorescens (IIF) med transfekterade celler.
Svar Resultatet anges som positiv eller negativ. Positivt resultat titreras (serum).
Tolkning LGI-1 är en subenhet i kaliumkanalskomplexet (VGKC). Antikroppar mot LGI-1 har rapporterats förekomma vid klassisk autoimmun encefalit och epilepsi. Antikroppar mot LGI-1 anses vara de näst vanligast förekommande vid autoimmun encefalit efter antikroppar mot NMDAR. Autoantikroppar mot LG-1 påvisas något oftare hos män, ålder vid diagnos har varierat mellan 30-80 år (median 60 år). LGI-1 antikroppar är associerade med tumörer (lung, tymom men även andra tumörformer) i 25-31% av fallen.
LGI-1 räknas till gruppen extracellulära antigen. Generellt sett är behandling med immunoterapi oftare effektiv vid autoantikroppar riktade mot extracellulära antigen än vid autoantikroppar mot intracellulära antigen. Antikroppstitrar kan användas för att följa behandlingseffektivitet. Uppföljning med cancerdiagnostik rekommenderas.
Antikropparna riktade mot LGI-1 bedöms vara Lower-risk antibodies med en förekomst på <10% för en underliggande cancer och positivitet ger 0 poäng i PNS score enligt Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
Referenser
- Lai, Huijbers, Lancaster, et al. Investigation of LGI1 as the antigen in limbic encephalitis previously attributed to potassium channels: a case series. Lancet Neurol 2010;9:776-785. PMID 20580615.
- Irani SR, Alexander S, Waters P, et al. Antibodies to Kv1 potassium channelcomplex proteins leucine-rich, glioma inactivated 1 protein and contactin-associated protein-2 in limbic encephalitis, Morvan’s syndrome and acquired neuromyotonia. Brain 2010;133:2734-2748. PMID 20663977.
- Dalmau J, Geis C, Graus F. Autoantibodies to Synaptic Receptors and Neuronal Cell Surface Proteins in Autoimmune Diseases of the Central Nervous System. Physiol Rev. 2017 Apr;97(2):839-887. PMID: 28298428;
- Graus F, et al. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. Neurol Neuroimmunol Neuroinflamm. 2021 May 18;8(4):e1014. PMID: 34006622