Lyme disease patients' serum contains IgM antibodies to Borrelia burgdorferi that cross-react with neuronal antigens.

Serum from patients with neurologic manifestations of Lyme disease had serum IgM antibodies that bound to normal human axons, whereas binding was absent or weak in patients without neurologic findings. Antiaxonal binding could be eliminated by absorption with Borrelia burgdorferi. A murine monoclonal antibody to the borrelial flagellin also bound to human axons.