Synovial origins of Rice bodies in joint fluid.

Rice bodies and synovia obtained from knee joints of rheumatoid arthritis patients were solubilized by limited pepsin treatment. The quantity of each type of collagen in both tissues was determined by differential salt precipitation, cyanogen bromide peptide analysis, and SDS polyacrylamide gel electrophoresis. Rice bodies and synovial membrane contained equal proportions of Type I and III collagens with trace amounts of Type "A-B" collagen.