Pristane-induced arthritis in the rat.

A chronic relapsing arthritis develops after a single subcutaneous injection of small amounts of pristane; the pristane induced arthritis (PIA) model in the rat. PIA is characterized by a sudden onset of disease 2 wk after induction. The main pathological features of PIA include edema accompanied by an acute phase response, infiltration into the joint of mononuclear and polymorphonuclear cells, pannus formation, and erosion of cartilage and bone. PIA is a disease that is largely T-cell dependent that can be adoptively transferred by activated CD4+ T-cells. PIA in rats is followed clinically by macroscopic scoring and is characterized by an early acute phase of severe inflammation after onset that eventually gradually disappears to be followed by less severe relapsing phases of new inflamed joints and increasing cartilage erosion and joint deformity. PIA can be diagnosed by biochemical analyzes in plasma that reflects systemic inflammation (alpha1-acid glycoprotein (AGP) and IL-6) and cartilage erosion (COMP).