Major histocompatibility proteins, anti-Hu antibodies, and paraneoplastic encephalomyelitis in neuroblastoma and small cell lung cancer

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Abstract
Background. Patients with neuroendocrine-related tumors and paraneoplastic encephalomyelitis (PEM) or paraneoplastic sensory neuronopathy (PSN) develop high titers of antibodies, called anti-Hu, against neuronal proteins expressed in their tumors, usually small cell lung cancer (SCLC). These tumors appear to be more indolent than those not associated with anti-Hu antibodies. The aims of this study were to determine 1) if patients with neuroblastoma (N8) also have anti-Hu antibodies, 2) the correlation between antibody titer and survival, and 3) if coexpression of Hu antigens and major histocompatibility proteins (MHC) by the tumor correlates with the development of anti-Hu associated PEM/PSN. Methods. Using immunohistochemistry and Western blot analysis, the sera of 109 patients with NB whose neurologic condition was concealed at the time of the study were examined for the presence of anti-Hu antibodies. The expression of Hu antigens and MHC proteins in 50 nonselected NB and 26 SCLC (16 known to be from seropositive and 10 from seronegative patients) was examined using immunohistochemistry. Results. Four Stage 4 NB patients were seropositive and had longer survival (median 86 months) than 71 seronegative patients in the same age group and with the same tumor stage (median survival, 28.5 months). Seventy-eight percent of NB and all SCLC expressed Hu antigens. Overall, 17 of 20 tumors from seropositive patients expressed both Hu and MHC Class I proteins, but only 4 of 30 tumors from seronegative patients expressed both proteins (P < 0.0001). Conclusions. 1) Some patients with NB develop anti-Hu antibodies; a search for that type of tumor is indicated in seropositive children, 2) most NBs and SCLCs express Hu antigens but only a few are associated with anti-Hu antibodies, and 3) Class I MHC expressed by some Hu antigen-bearing tumors may play a role in the development of anti-Hu associated PEM/PSN.