Analysis of autoantibody binding to 52-kd paraneoplastic cerebellar degeneration-associated antigen expressed in recombinant proteins.

A 52-kd neural antigen was reported to be recognized by anti-Purkinje cell antibodies in serum of a patient with paraneoplastic cerebellar degeneration associated with uterine carcinoma. In this study, we demonstrate that this neural antigen is recognized by antibodies known as anti-Purkinje cell antibody type I (PCAb Type I) and anti-YO. The latter's antigen is reported to be specific for the 62- to 64-kd antigen CDR62. Assuming that the 52-kd and 62- to 64-kd antigens share a common epitope(s) recognized by all of these antibodies, we examined the antigenic region on the 52-kd protein by immunoblots with deletion fragment proteins of the recombinant 52-kd protein. A major epitope was localized in the region of amino acid residues 94 to 133 of the 52-kd protein, which is the site of a leucine zipper motif. The potential pathogenicity of PCAb Type I is discussed.