What destroys the joint in rheumatoid arthritis?

The immunological disturbance in rheumatoid arthritis (RA) gives rise to a nonspecific inflammatory reaction mediated by cells and cytokines. This immunological nonbacterial synovitis, however, does not destroy the articular cartilage. The destruction of joint structures is the effect of tumor-like aggressive synoviogenic cell elements (TLP). These TLP formations are not observed in any other type of arthritis. TLP formations are strictly avascular and short-lived. After they have decayed, a collagenous pannus remains. Invasion and destruction of joint structures are brought about by several types of proteases, synthesized and secreted by highly active TLP cells. The TLP formations possess more than twice the affinity for adjacent bone than for the articular cartilage. In these formations, four oncogenes could be identified. In the course of RA disease, TLP formations can recur. Thus, the joint damage can summate with time. The oncological character of the aggressive process in RA demands new therapeutical considerations to protect RA patients from destruction of their joints.