A comparison of tissue-based and recombinant protein-based assays for detecting PCA-Tr/DNER-IgG.

Purkinje cell cytoplasmic antibody, type Tr (PCA-Tr) is typically encountered in patients with Hodgkin lymphoma–related paraneoplastic cerebellar ataxia.1 Immunohistochemical techniques, including indirect immunofluorescence assays (IFAs), employing rodent brain as substrate, reveal a specific immunoglobulin G (IgG) binding pattern on cerebellar Purkinje cell cytoplasm and molecular layer dendritic spines.2 PCA-Tr characterization as delta/notch-like epidermal growth factor–related receptor (DNER)–IgG has permitted antigen-specific assay development.3 With rare exception, the phenotype encountered is cerebellar ataxia among patients with Hodgkin lymphoma. Tr autoimmunity is occasionally reported in some patients with noncerebellar neurologic disorders, and in others with non-Hodgkin lymphoma.4 Acknowledgment: The authors thank John Schmeling for technical support and the Center for Individualized Medicine and Department of Laboratory Medicine and Pathology, Mayo Clinic, for funding.