INDIVIDUAL TEST 772
AMPA Receptor 1/2 Antibodies (IgG)
Indication
Suspicion of autoimmune encephalitis and paraneoplastic syndrome
Sample material
Serum
- Minim. volume: 0.5 mL
CSF
- Minim. volume: 0.5 mL
Transport
Within Sweden
- room temperature
International
- cold
Method
Cell-based assay (CBA), Indirect immunofluorescence (IIF)
Reference interval
Serum
CSF
- negative
Result
Results are reported as negative or positive. A positive result is followed by a titer (serum).
Interpretation
Antibodies against AMPA 1/2 receptors can be seen in paraneoplastic syndrome and classical autoimmune encephalitis, but cases of isolated psychoses have also been described. There are relatively few cases published, of which 90% have been women. Age at diagnosis has been 38-87 years (median 60 years). The antibodies have been associated with tumors (lung, breast, and thymoma) in 70% of the cases. Antibodies may occur together with other autoantibodies in around 60% of cases (antibodies against ANA, GAD-65, cardiolipin, VGCC, SOX1, CV2/CRMP5, and TPO).
The AMPA receptors are included in the group of extracellular antigens. Generally, immunotherapy is more often effective in autoantibodies directed against extracellular antigens than in autoantibodies against intracellular antigens. Screening for cancer diagnosis is recommended.
Antibodies against AMPA 1/2 receptor are graded as Intermediate-risk antibodies with a frequency of >50% of underlying cancer, and a positive result yields a 2-point PNS score according to Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
References
- Leypoldt F et al. Ann N Y Acad Sci. 2015. Autoimmune encephalopathies. PMID: 25315420
- Dalmau J et al. Physiol Rev. 2017. Autoantibodies to Synaptic Receptors and Neuronal Cell Surface Proteins in Autoimmune Diseases of the Central Nervous System. PMID: 28298428
- Dalmau J et al. Lancet Neurol. 2019. An update on anti-NMDA receptor encephalitis for neurologists and psychiatrists: mechanisms and models. PMID: 31326280
- Graus F et al. Neurol Neuroimmunol Neuroinflamm. 2021. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. PMID: 34006622
- Flanagan EP et al. JAMA Neurol. 2023. Autoimmune Encephalitis Misdiagnosis in Adults. PMID: 36441519
Last updated: 2024-08-12
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ENSKILD ANALYS 772
AMPA receptor 1/2-antikroppar (IgG)
Indikation
Misstanke of autoimmun encefalit och paraneoplastiskt syndrom
Provmaterial
Serum
- Minim. volym: 0,5 mL
Likvor
- Minim. volym: 0,5 mL
Transport
Inom Sverige
- rumstemperatur
Internationellt
- kylt
Metod
Cell-based assay (CBA), indirekt immunofluorescens (IIF)
Referensintervall
Serum
- <1:10 negativt
Likvor
- negativt
Resultat
Resultat anges som negativt eller positivt. Positivt resultat titreras (serum).
Tolkning
Antikroppar mot AMPA 1/2 receptorer kan ses vid paraneoplastiska syndrom och autoimmun encefalit men fall av isolerade psykoser har också beskrivits. Det finns ett fåtal fall publicerade varav 90% har varit kvinnor. Ålder vid diagnos har varit 38-87 år (median 60 år). Antikropparna har varit associerade med tumörer (lung, bröst och tymom) i 70% av fallen. Antikropparna kan förekomma tillsammans med andra autoantikroppar i runt 60% av fallen (antikroppar mot ANA, GAD-65, kardiolipin, VGCC, SOX1, CV2/CRMP5 och TPO).
AMPA receptorerna räknas till gruppen extracellulära antigen. Generellt sett är behandling med immunoterapi oftare effektfull vid autoantikroppar riktade mot extracellulära antigen än vid autoantikroppar mot intracellulära antigen. Uppföljning med cancerdiagnostik rekommenderas.
Antikroppar riktade mot AMPA 1/2 receptorer bedöms vara Intermediate-risk antibodies med en förekomst på >50% för en underliggande cancer och positivitet ger 2 poäng i PNS score enligt Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes.
Referenser
- Leypoldt F et al. Ann N Y Acad Sci. 2015. Autoimmune encephalopathies. PMID: 25315420
- Dalmau J et al. Physiol Rev. 2017. Autoantibodies to Synaptic Receptors and Neuronal Cell Surface Proteins in Autoimmune Diseases of the Central Nervous System. PMID: 28298428
- Dalmau J et al. Lancet Neurol. 2019. An update on anti-NMDA receptor encephalitis for neurologists and psychiatrists: mechanisms and models. PMID: 31326280
- Graus F et al. Neurol Neuroimmunol Neuroinflamm. 2021. Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes. PMID: 34006622
- Flanagan EP et al. JAMA Neurol. 2023. Autoimmune Encephalitis Misdiagnosis in Adults. PMID: 36441519
Senast uppdaterat: 2024-08-12