Anti-Tr antibodies as markers of paraneoplastic cerebellar degeneration and Hodgkin's disease

Background: Preliminary studies suggested that anti-Tr antibodies identify patients with paraneoplastic cerebellar degeneration (PCD) and Hodgkin disease (HD). Objective: To extend the clinical-immunologic analysis to 28 patients with anti-Tr antibodies. Methods: Anti-Tr antibodies were detected by immunohistochemistry. A competitive inhibition assay was used to ascertain if anti-Tr antibodies of different sera identify common epitopes. Anti-Tr immunoglobulin G (IgG) subclass distribution was determined by immunohistochemistry using monoclonal antibodies against human IgG isotypes. Tr immunoreactivity was analyzed in tumor sections using biotinylated anti-Tr IgG. Results: Median age of the 28 patients was 61 years (range 14 to 75 years) and 22 were male. A cerebellar syndrome was present in 27 patients and a possible limbic encephalitis in one. HD was diagnosed in 25 patients. No tumor was found in three patients; the autopsy of one of them disclosed severe loss of Purkinje cells without inflammatory infiltrates. Anti-Tr antibodies spontaneously disappeared in all patients without tumor and in 10/10 patients after successful HD treatment. Anti-Tr antibodies were absent in the serum but positive in the CSF of two patients. All positive anti-Tr sera inhibited the immunoreactivity of biotinylated anti-Tr IgG. The predominant isotypes of anti-Tr were IgG1 and IgG3. Only 1 out of the 15 HD samples studied presented anti-Tr positivity that was localized in some Reed-Sternberg cells. Conclusions: This study confirms the strong association between anti-Tr antibodies and PCD associated with HD. Anti-Tr antibodies from different patients recognize similar epitopes. Unlike other antineuronal antibodies, anti-Tr antibodies can be detected in the CSF but not in the serum and may spontaneously disappear during the follow-up, and Tr immunoreactivity is usually lacking in the tumor.