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Objective: Voltage-gated potassium channel antibodies are implicated in limbic encephalitis and currently included in first-episode psychosis organic screening guidelines. Individuals with high-positive voltage-gated potassium channel titres most commonly present with neurological symptoms as well as sleep, cognitive, behaviour, psychosis and mood disturbance. The significance of low-positive voltage-gated potassium channel antibody titres in psychiatric patients is unclear and has not been previously examined. We aim to describe a statewide cohort of psychiatric patients with low- and high-positive voltage-gated potassium channel titres and explore if this finding influenced clinical management and patient outcomes. Methods: A retrospective review of all voltage-gated potassium channel antibodies testing performed in public psychiatric services in Queensland, Australia, with comparison of the clinical presentation and long-term outcomes of low- and high-positive voltage-gated potassium channel titre cases. Specific antigen targets (leucine-rich glioma-inactivated protein 1 and contactin-associated protein 2 antibodies) were also assessed. Results: The overall prevalence of voltage-gated potassium channel antibody positivity in Queensland, public, psychiatric service testing was 0.3% (14/4098), with 12 cases of low-positive voltage-gated potassium channel titre, 2 cases of high-positive (leucine-rich glioma-inactivated protein 1 antibody positive) cases and a voltage-gated potassium channel negative contactin-associated protein 2 antibody positive case. No low-positive case developed neurological abnormalities or had abnormal paraclinical investigations. In comparison, both high-positive voltage-gated potassium channel/leucine-rich glioma-inactivated protein 1 cases and the contactin-associated protein 2 antibody positive case rapidly developed neurological symptoms, had abnormal paraclinical testing and improved only with immunotherapy. There was no later development of encephalitic symptoms in the low-positive cases over an average of 1067 days follow-up. Conclusion: Voltage-gated potassium channel antibody–associated limbic encephalitis was rare, and always associated with high antibody titres. Low-positive titres were not associated with the development of encephalitis over a long period of follow-up. The value of universal voltage-gated potassium channel antibody screening is unclear, and further prospective studies in first-episode psychosis populations are required. [ABSTRACT FROM AUTHOR]

Background: Soluble triggering receptor expressed on myeloid cells-2 (sTREM-2) is a marker of macrophage and microglial activation and is increased in the cerebrospinal fluid (CSF) in multiple sclerosis (MS). Objective: To determine the relationships among sTREM-2, T cell activation, neuroaxonal damage and clinical features of MS. Methods: Enzyme-linked immunosorbent assays were used to measure the levels of sTREM-2, soluble CD27 (sCD27, a marker of T cell activation), neurofilament light chain (NfL) and phosphorylated neurofilament heavy chain (pNfH) in the CSF of 42 patients with MS (including nine with clinically isolated syndrome) and 15 patients with other neurological diseases (OND) and in the serum of 164 patients with MS, 87 patients with OND and 62 healthy controls. Results: sTREM-2 was significantly elevated in the CSF (p = 0.012), but not in the serum, in MS compared to OND. In MS, CSF sTREM-2 correlated positively with CSF sCD27 (p = 0.005), CSF NfL (p = 0.0001), CSF pNfH (p = 0.0006), Expanded Disability Status Scale (EDSS) score (p = 0.0079) and MS Severity Score (MSSS) (p = 0.0006). Conclusion: In MS the level of sTREM-2 in the CSF is related to measures of T cell activation (sCD27), neuroaxonal damage (NfL and pNfH), disability (EDSS) and disease severity (MSSS). [ABSTRACT FROM AUTHOR]

This report will detail a case of immune-mediated encephalitis in the context of daclizumab therapy. Daclizumab is a humanised monoclonal antibody which, prior to its recent worldwide withdrawal due to safety concerns, was utilised as a disease-modifying therapy in relapsing-remitting multiple sclerosis. The withdrawal of this therapy was prompted by concerns over 12 cases of serious immune-mediated adverse reactions in the central nervous system. We report an additional case, including clinical data and results of neuroimaging, cerebrospinal fluid (CSF) examination and brain biopsy. [ABSTRACT FROM AUTHOR]

The article offers information on N-methyl-d-aspartate neurotransmitter cell surface receptors (NMDAR) and its testing in patients with early psychosis. Topics discussed include the diagnosis of anti-NMDAR encephalitis using NMDAR antibodies in plasma and cerebrospinal fluid (CSF); the uncertainty about the role of NMDAR antibodies in psychosis; and the voltage-gated potassium channel (VGKC) antibodies.