Antibodies to chondroitin sulfate C: a new detection assay and correlations with neurological diseases.

Antibodies to chondroitin sulfate C (ChS C) have been previously associated with sensory axonal neuropathy. Investigation of these antibodies has, however, been limited by the lack of a sensitive and reliable test for their detection. We developed a new enzyme-linked immunoassorbent assay (ELISA), where biotinylated ChS C was made to adhere to avidin-coated microwells. The new ELISA showed a much greater sensitivity than other currently available ELISAs for detection of anti-ChS C antibodies. A total of 480 sera (466 patients and 14 normal volunteers) were tested at increasing dilutions for anti-ChS C antibody activity. Normal subjects had IgM anti-ChS C antibody titers of up to 3,200 and mildly elevated titers of 6,400 were seen in a variety of diseases. Eleven patients had titers of 12,800 or higher. These included seven patients with sensory axonal neuropathy, three with amyotrophic lateral sclerosis and one with corticobasal ganglionic degeneration. These studies indicate that anti-ChS antibodies do occur in patients with axonal sensory neuropathy, but are not limited to that disease.