Hepatitis C virus infection and myositis: a polymerase chain reaction study

Muscle biopsy tissue from a patient with chronic hepatitis, who was hepatit is C virus (HCV) positive and showed slight weakness of the right arm and l eg en associated with increased serum creatine kinase levels, was studied u sing immunocytochemical and polymerase chain reaction (PCR) techniques. Mus cle biopsy showed changes compatible with an inflammatory myopathy. Immunoh istochemical studies included the use of monoclonal antibodies against huma n T lymphocytes, macrophages, immunoglobulins, major histocompatibility com plex class I molecules (MHC-I), and the neoantigens of the terminal C5b-9 c omplement membrane attack complex (MAC). In addition to confirming the pote ntial importance of cytotoxic T cells and MHC-I antigen expression in induc ing muscle pathology, we demonstrated MAC deposition and the presence of HC V-RNA in the muscle of our patient, suggesting that direct involvement of t he virus leading to complement activation might be important in inducing mu scle damage.