C5b‐9 TERMINAL COMPLEX ACTIVATION IN CHRONIC INFLAMMATORY DEMYELINATING NEUROPATHY

Abstract

Background: Complement activation plays an important role in the pathogenesis of some peripheral nerve disorders. Activated terminal attack complex (C5b‐9) was detected in the cerebrospinal fluid and in peripheral nerve of patients with Guillain‐Barré syndrome, suggesting its involvement in the tissue‐damaging processes. Recently, complement activation products have been described on and around amyloid deposits in acquired and hereditary amyloid neuropathy in which this may contribute to the injury of axons. Objective: The aim of this study was the investigation of patients with CIDP by immunohistochemistry for evidence of complement activation. Materials and Methods: We performed immunohistochemistry on frozen nerve specimens of 5 patients with CIDP compared with 3 patients with chronic inflammatory axonal neuropathy and 3 with HSMN, by using a panel of monoclonal antibodies raised against C5b‐9, macrophages, B, CD4 and CD8 cell subsets. Normal frozen nerves were used as controls. Results: C5b‐9 expression was found with strong signal in the perineurium, endoneurial vessel walls and in some epineurial vessels in inflammatory demyelinating and axonal neuropathies. C5b‐9 immunoreactivity was also present in the perineurial cells of HSMN and, with very low intensity, in normal control nerves. Conclusion: Our findings suggest that complement activation is an important factor in the cascade of events leading to immune‐mediated demyelination in CIDP and axonal damage in some chronic axonal neuropathies. Less‐specific positive perineurial immunoreactivity was detected in HSMN. Evidence of complement activation in inflammatory neuropathies may be helpful in the diagnosis.