Autoantibodies against the amino terminal of alpha-enolase are a useful diagnostic marker of Hashimoto's encephalopathy.

We investigated autoantibodies and their epitope(s) in Hashimoto's encephalopathy associated with Hashimoto's thyroiditis. In a proteomic analysis, they proved to recognize alpha-enolase. We further searched the epitope region in alpha-enolase using different regions of recombinant proteins expressed in cultured human cells. The amino terminal region was recognized by autobodies from a much higher proportion of patients with Hashimoto's encephalopathy (83.3%; 5/6) than from patients with Hashimoto's thyroiditis (11.8%; 2/17), and not at all by sera from controls (25 healthy individuals and 25 controls with other neurological disorders) (0%; 0/50). Neither the carboxyl terminal nor the mid-region of alpha-enolase showed specificity for Hashimoto's encephalopathy. Autoantibodies against the amino terminal of alpha-enolase are a useful diagnostic marker for Hashimoto's encephalopathy.