The mycobacterial 65 kDa heat shock protein (Hsp65) is of critical significance in the experimental model of adjuvant arthritis (AA), which is an extensively studied form of experimental arthritis with a close histopathologic resemblance to rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) (20-22). The gene discussed is HSPD1; the disease is rheumatoid arthritis.