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Updated: Oct 5, 2025
Hippocampal Neuronal Cultures to Detect and Study New Pathogenic Antibodies Involved in Autoimmune Encephalitis
Published on: June 2, 2022
The importance of tissue-based assay in the diagnosis of autoimmune encephalitis
Avi Gadoth1,2, Yahel Segal3, Yael Paran4,5
1Department of Neurology, Tel-Aviv Medical Center, Affiliated to the Sackler Faculty of Medicine, Tel Aviv University, 6 Weizmann Street, 6423906, Tel-Aviv, Israel. avig@tlvmc.gov.il.
Background:
The evaluation of autoimmune encephalitis (AIE) usually includes antibody testing with commercial kits capable of detecting only preselected antibodies. A non-antigen-specific assay may help detect other antibodies. In this study, we evaluate the utility and clinical relevance of an immunofluorescence assay (IFA) in the evaluation of AIE.
Methods:
Immunofluorescence assay was performed on 1949 patients' serum/CSF between 2017 and 2020 and clinical relevance was designated to each case based on clinical course, suggested criteria and ancillary testing.
Results:
Sixty-one patients (3.1%) had positive serum IFA, positive CSF, or both. Twenty-eight out of 42 patients who were positive only on IFA were designated as clinically relevant (67%), 8 inconclusive (19%), and 6 non-relevant (14%). Pleocytosis was significantly higher in the clinically relevant cases (74% vs. 20% for non-clinically relevant cases). Encephalopathy was the most common presentation (36%), followed by cerebellar syndrome (32%) and seizures (25%). The initial diagnosis changed due to IFA results in 13/28 (46%) cases and IFA result led to the initiation or modification of treatment in all cases (68% and 43%, respectively). Twenty-five patients were treated with 1st line immunotherapy and 12 with 2nd line immunotherapy, with 92% responding to treatment. Twenty-six clinically relevant patients underwent cancer workup: seven (25%) had confirmed malignancy and three had high suspicion of malignancy (total of 37%).
Conclusion:
Non-antigen-specific assays, such as IFA, can identify antibodies not detected in commercially available kits and therefore are recommended in the evaluation of autoimmune encephalitis.
