Abstract
A water-inoil emulsion containing a synthetic adjuvant, N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) induced typical adjuvant-induced arthritis in euthymic rats but not in athymic nude rats. The nude rats as well as euthymic rats, however, developed acute polyarthritis with a 100% incidence after consecutive intravenous injections of 6-O-acyl MDP, such as L18MDP or [B 30] -MDP. This acute polyarthritis rapidly subsided after stopping the injections but flared up within 24 hours after booster injection of 6-O-acyl MDP not of MDP.
The histological features of the acute polyarthritis revealed acute exudative synovitis, subsynovitis and tendinitis.
The present finding that adjuvant active MDP and its derivatives induced transient leukocytosis suggests that this new model of arthritis may result from direct inflammatory reaction to MDP molecules deposited in the diseased joints.
