Rheumatoid and normal synovial tissue in longterm culture. Evidence of cell heterogeneity and an approach to quantitation of of populations and the effect of passage.

Longtern monolayer cultures of cells derived from explants of 21 normal and 31 rheumatoid synovial tissue specimens were studied and shown to be morphologically heterogeneous. The cultures were defined according to their cell size and their buoyant density as determined by separation on Ficoll density gradients. The investigations demonstrate that changes in these populations occurred with each passage of the cell lines. These findings emphasize the importance of using cultures of the same cultural age and passage for any comparative s tudy. The techniques described are useful for separating and defining the populations present in synovial tissue tissue cultures.