Tissue distribution of pathological lesions and Hu antigen expression in paraneoplastic sensory neuronopathy

We investigated the distribution of lesions and Hu antigen expression in two autopsied cases of anti-Hu antibody-positive paraneoplastic sensory neuronopathy (carcinomatous subacute sensory neuropathy). Pathological changes in both patients were limited to the primary sensory neurons, some of the sympathetic ganglia and hippocampal regions. The lesions showed a multifocal distribution that differed among the spinal segmental levels and in the individual dorsal root ganglia as well as in the nerve fascicles. Western blot analysis of the patients’ serum revealed that Hu antigens were extensively and widely expressed throughout the central nervous system, sensory and sympathetic ganglia and cancer cells, but not in the non-neural visceral tissues. Reverse transcriptase-polymerase chain reaction also showed that the Hu D, Hu C, Hel-N1 and Hel-N2 mRNAs were extensively and widely expressed through the neural tissues and cancer cells, but not in the visceral tissues. Thus, the distribution of antigen expression was very different from that of the lesions. Taken together with the distribution of lesions and Hu antigen expression, it is suggested that factors other than anti-Hu antibodies are also involved in the pathogenesis of this neuronopathy.