The intra-articular residual rate of 131I-fibrinogen and microautoradiographs of the synovial tissue in rheumatoid arthritis.

In this study, 131I-labeled human plasma fibrinogen (200 μCi) was injected intravenously into 21 patients with rheumatoid arthritis and 10 control patients without rheumatic diseases. The residual rates of radio-iodinated fibrinogen in the knee joints were calculated by measuring with a scintillation counter the microautoradiographs of the synovial tissue obtained by punch biopsy from the knee joints. The residual rates in the knee joints without as well as with objective symptoms of RA were higher than in control patients. Radio-iodinated fibrinogen was demonstrated on the synovial villous surface, on the area of inflammatory cellular infiltration and stromal necrosis, and on the perivascular region of the synovial tissue from the knee joints of patients with RA, not only with, but also without clinical objective symptoms and histopathologic findings of fibrinoid necrosis, vascular superficial fibrinoid coating and fibrinoid degeneration of vascular wall. It is suggested that fibrinogen plays a role even...