Discussion
Our results demonstrate a direct effect of anti-contactin-1 autoantibodies on the surface expression of contactin-1 and sodium currents in dorsal root ganglion neurons. This may be the pathophysiologic correlate of sensory ataxia reported in these patients.
Methods
Immunocytochemistry including structured illumination microscopy and immunoblotting was used to determine expression levels of contactin-1 and/or sodium channels after long-term exposure to autoantibodies from 3 seropositive patients. For functional analysis of sodium channels, whole-cell recordings of sodium currents were performed on dorsal root ganglion neurons incubated with anti-contactin-1 autoantibodies.
Results
We found a reduction in contactin-1 expression levels on dorsal root ganglion neurons, cerebellar granule neurons, and contactin-1-transfected human embryonic kidney 293 cells and decreased dorsal root ganglion sodium currents after long-term exposure to anti-contactin-1 autoantibodies. Sodium channel density did not decrease.