Short communicationImmunohistochemical screening for antibodies in recent onset type 1 narcolepsy and after H1N1 vaccination

•Narcolepsy type 1 is hypothesised to be an autoimmune disease.•Screening for antibodies against hypocretin neurons using immunohistochemistry•Serum of 21 narcolepsy type 1 patients close to disease onset•No antibodies against hypocretin neurons could be detected.

Narcolepsy type 1 patients typically have undetectable hypocretin-1 levels in the cerebrospinal fluid (CSF), as a result of a selective loss of the hypocretin containing neurons in the hypothalamus. An autoimmune attack targeting hypothalamic hypocretin (orexin) neurons is hypothesised. So far, no direct evidence for an autoimmune attack was found. One of the major limitations of previous studies was that none included patients close to disease onset. We screened serum of 21 narcolepsy type 1 patients close to disease onset (median 11 months), including 8 H1N1 vaccinated patients, for antibodies against hypocretin neurons using immunohistochemistry. No autoantibodies against hypocretin neurons could be detected.