[Virus-like particles in cultures of rheumatoid synovial cells]

Cultures of synovial cells from 8 patients with classical or determined rheumatoid arthritis and 3 patients with non-rheumatoid arthrosis were examined electron microscopically. Cells of the monolayer formed upon prolonged incubation of tissue pieces had the conventional ultrastructure of synovial cells. In 2 out of 8 cultures of rheumatoid synovial cells after 14 days of incubation, budding virus-like particles with the external diameter of 100-120 nm were observed. Morphologically these particles were very similar to retroviruses. Isolated particles had a buoyant density in sucrose of 1.15-1.17 g/cm3.