Antibody types and IgG subclasses in paraneoplastic neurological syndromes

Three major patterns of antineuronal antibody response have been identified in patients with paraneoplastic neurological syndromes: Type I ('Anti-Yo') , associated with cerebellar degeneration in the setting of breast or gynec ological cancer, Type IIa ('anti-Hu') associated with encephalomyeloneuriti s in patients with small cell carcinoma of the lung, and Type IIb, ('anti-R i') associated with breast cancer. We have employed immunofluorescence meth ods to determine the antibody classes and the IgG subclasses which react wi th neurons in each of these patterns of paraneoplastic antibody response. I n this study, IgG was the only antibody class identified; IgM and IgA antib odies were not found. IgG1 was the major subclass represented and was found in 9/9 patients with Type I antibody response, 26/27 patients with Type II a antibody response, and 3/3 patients with Type IIb antibody response. Many patients also exhibited positive staining for IgG2 and IgG3. Trace amounts of IgG4 antineuronal antibodies were detected in a single patient with Typ e I antibody response; IgG4 antibodies were not found in other patients. Pa tients with paraneoplastic neurological syndromes exhibit an antibody respo nse which is overwhelmingly IgG and is comprised predominantly of IgG subcl asses capable of fixing complement. The role of these antibodies in the pat hogenesis of paraneoplastic neurological disease remains uncertain. Publish ed by Elsevier Science B.V.