Isolation of cytomegalovirus from synovial cells of a patient with rheumatoid arthritis.

Synovial cells from the joint of a patient with rheumatoid arthritis (RA) showed foci of cytopathic effects during their 3rd subculture in vitro. Electron microscopy of these cells revealed findings characteristic for cytomegalovirus (CMV), and immunofluorescent staining using antiserum specific for CMV was positive. The patient had classical seropositive RA, was not taking immunosuppressive agents, and had no clinical manifestations of CMV disease at the time of synovectomy 3 months earlier. Titers of antibodies to CMV were studied in the sera and synovial fluids of 3 additional patients with RA, and in 1, elevated IgM antibodies to CMV were found, indicating recent infection. Additional studies for CMV in RA are indicated.