A novel relationship between plasma kininogen and rheumatoid disease

Plasma kininogen levels in the peripheral venous blood of untreated patients with active rheumatoid disease was found to be more than twice the levels measured in healthy normal individuals or in convalescing uncomplicated fracture patients. Treatment with oral indomethacin or aspirin lowered the kininogen levels nearly to normal. Sequential studies showed that the fall in kininogen was very rapid, occurring within 1-2 hours of ingestion of drug, and was parallelled by reduction in the clinical indices of inflammation. Control studies showed that the kininogen changes were not due to changes in plasma volume or non-specific changes in plasma protein concentration. Indomethacin treatment had no effect on plasma kininogen levels in healthy volunteers. The significance of this finding will be discussed.