Normal serum levels of immune complexes in postpolio patients

OBJECTIVE: The pathophysiology of the postpolio syndrome is not fully understood. Increased cytokine levels in cerebrospinal fluid and peripheral blood indicate a systemic inflammatory process. Decreased cytokine levels and the clinical effect of intravenous immunoglobulin treatment further indicate an inflammatory/immunological pathogenesis. The aim of the present study was to evaluate whether an autoimmune process follows the initial infection, by means of analyzing immune complexes. PATIENTS AND METHODS: Circulating immune complexes were analyzed from blood samples of 20 postpolio patients and 95 healthy controls. To compensate for differences in age between patients and controls, a sub-analysis was performed using only the 30 oldest controls. Tumor necrosis factor-inducing properties of polyethylene glycol-precipitated immune complexes were compared between the postpolio patients and 10 healthy controls. RESULTS: When comparing levels in postpolio patients to the whole control group, including the 30 oldest investigated, there were no statistically significant differences. No difference was found in tumor necrosis factor levels induced by immune complexes when comparing patients and controls. CONCLUSIONS: There was no increase in circulating immune complex or in tumor necrosis factor-inducing effects of circulating immune complex between postpolio patients and healthy controls, indicating that the postpolio syndrome is not due to an autoimmune reaction.