IMMUNIZATION WITH THE PARANEOPLASTIC ENCEPHALOMYELITIS ANTIGEN HUD DOES NOT CAUSE NEUROLOGIC DISEASE IN MICE

Paraneoplastic encephalomyelitis/paraneoplastic sensory neuronopathy ( PEM/PSN) associated with small cell lung cancer is characterized by hi gh serum and CSF titers of anti-neuronal (anti-Hu) antibodies and by i ntrathecal synthesis of anti-Hu IgG. A pathologic role for the anti-Hu antibodies in PEM/PSN is further suggested by reported intraneuronal accumulation of the antibodies in the nervous system of PEM/PSN patien ts at autopsy. We immunized SJIL/J mice, Lewis rats, and Hartley guine a pigs with purified recombinant HuD fusion protein. In spite of high- titer anti-HuD antibodies, neurologic and pathologic examination of th e animals was normal. Apparent uptake of purified IgG by neurons in th e brain proved to be artifactual.