The extra-articular deposition of fibrinogen antigenic material in patients with rheumatoid arthritis.

Experimental suction blisters were elicited on extensor and flexor sites or forearm skin of patients both with rheumatoid arthritis and without rheumatoid diseases. The blister fluid obtained was investigated, together with rheumatoid bursa fluid and rheumatoid noduli material by crossed and quantitative immunoelectrophoresis for fibrinogen antigenic material, plasminogen and inhibitors of fibrinolysis. In rheumatoid noduli and rheumatoid bursa fluid, fibrinogen degradation products identical with those previously described in rheumatoid synovial fluid and in bullous dermatosis were found (3, 14). On the other hand, no fibrinogen antigenic material was found in the experimental suction blisters. These results indicate that the fibrinogen degradation products in rheumatoid inflammatory exudate are probably not specific for a rheumatoid process, but rather part of a general mechanism in inflammation.