Levels of prostaglandins F2 alpha and E2 and thromboxane B2 in joint fluid in rheumatoid arthritis.

Prostaglandin F2 alpha (PGF2 alpha), prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) levels were determined by radioimmunoassay (RIA) in knee joint fluid in two groups of patients with classical or definite rheumatoid arthritis (RA). One group had no treatment for one week prior to the study. The second group consisted of patients who developed acute exudative arthritis despite the use of various non-steroidal anti-inflammatory drugs (NSAID). The main metabolites of PGF2 alpha in plasma and urine were measured in the untreated group. The conclusion to be drawn from this study are: 1) Treatment with NSAID effectively lowers PGF2 alpha and PGE2 and TXB2 levels in joint fluid. 2) Signs and symptoms of arthritis may persist in spite of lowered levels of PGF2 alpha and PGE2 in the joint fluid. 3) The main metabolites of PGF2 alpha in plasma and urine are above the low-normal limit in untreated patients. 4) The ratio TXB2/PG was low in untreated patients, suggesting that the thromboxane pathway is quantitatively minor in rheumatoid joint inflammation.