Anti-endothelial serum antibodies in a patient with Susac's syndrome

Susac's syndrome (SS) is a rare arteriopathy affecting the microvasculature of the brain, retina, and inner ear, resulting in encephalopathy, branch retinal artery occlusion and hearing loss. Anecdotal reports exist on SS being associated with a humoral immune response against endothelial cells. However, no original data has ever been published.

To analyze serum and CSF from a patient with SS for the presence of CNS auto-antibodies and, if present, to further characterize such antibodies immunologically.

Serum and CSF samples were examined by indirect immunofluorescence on adult mouse cerebrum, cerebellum, brain stem, and inner ear tissue sections, and IgG subclasses were determined.

Anti-endothelial antibodies were found at a titre of 1:960 in serum but not CSF. Antibodies belonged to the complement activating IgG1 subclass. Glucocorticoid treatment resulted in a decrease of titres (1:480), though the antibodies remained clearly detectable.

Our finding of anti-endothelial cell antibodies in a patient with SS is important in the light of previous pathological data suggesting that SS is associated with endothelial damage. Larger serological studies are now warranted to assess systematically the frequency and relevance of auto-antibodies in SS.