High levels of autoantibodies against catalase and superoxide dismutase in nasopharyngeal carcinoma.

INTRODUCTION: Autoantibodies against the antioxidant enzymes have been described in Epstein-Barr virus-associated diseases. Here, we hypothesize that Epstein-Barr virus (EBV), which is associated with nasopharyngeal carcinoma (NPC), induces anticatalase and/or antisuperoxide dismutase autoantibodies that inhibit catalase and/or superoxide dismutase activities and thereby contribute to the oxidative stress status described in this pathology. METHODS: Using a standard enzyme-linked immunosorbent assay (ELISA), the levels of immunoglobulin G (IgG), and M (IgM) directed against catalase and superoxide dismutase in the sera of 30 NPC patients and 30 healthy control individuals were evaluated. The antioxidative profile was tested among the same patients by measuring serum catalase and superoxide dismutase activities. To investigate the implication of EBV in the establishment of autoantibody production in NPC patients, a correlation study between serological testing for EBV viral capsid antigen immunoglobulin G (VCA IgG) and autoantibodies against both enzymes was undertaken. FINDINGS: The levels of IgG against superoxide dismutase and catalase were found to be increased in sera patients compared to controls (P<0.001). NPC patients exhibited decreased catalase (P<0.001) and superoxide dismutase activities (P<0.001) in their sera. However, a positive correlation between superoxide dismutase IgM antibody and IgG antibody titers to VCA (P<0.05, r=0.483, n=21) was found. A positive correlation between catalase (IgM) antibodies and IgG antibody titers to VCA (P<0.05, r=0.546, n=30) was also found. CONCLUSION: High levels of anticatalase and antisuperoxide dismutase antibodies in the sera of NPC patients were found.