Electron microscopic and immunochemical studies in a patient with hepatitis C virus infection and mixed cryoglobulinemia type II

The authors describe patient with hepatitis C virus (HCV) infection and mixed cryoglobulinemia type II in whom multiorgan failure was associated with deposits of typical, electron-microscopically visualized paracrystalline tubules in the organs studied. The patient's plasma cryoprecipitate was comprised of monoclonal IgM rheumatoid factor, polyclonal IgG, HCV RNA, and complement component C3. Of the polyclonal IgG, almost half was anti-HCV. The molar ratio between IgG and IgM was approximately 1.5 to 1. On peripheral blood films the cryoprecipitate formed cloudlike structures, which may be a useful diagnostic clue in mixed cryoglobulinemia type II. The ultrastructure of plasma cryoprecipitate and of deposits in skin, renal glomerular capillaries, and blood monocytes was identical. The cross-sectional diameter of the tubules was 30.7 ± 1.6 nm (mean ± 1 SD), and they appeared to be surrounded by eight electron-lucent dots. Deposition in organs of complexes containing HCV antigens and antibodies, rheumatoid factor, and C3 contributed to the multiorgan disease in this patient.