Background: Despite ongoing intensive research using sophisticated new molecular tools and methods, the pathogenesis of autoimmune diseases such as rheumatoid arthritis (RA) is still not completely understood.
Hypotheses: In this paper the two favorite hypotheses of the pathogenesis of rheumatoid arthritis currently discussed are introduced and compared. Hypothesis 1 is focussing on the central role of the T cells and T cell dependent phenomena in the pathogenetic scenario of RA. In contrast, hypothesis 2 stresses the role of altered synovial fibroblasts and their specific features critical for the destruction of inflamed joints. Both hypotheses are thoroughly discussed and suggestions for further research activities are made.
Conclusion: Insights in the pathogenesis of RA provide options to develop new therapeutic strategies aimed at the inhibition of pathogenetic relevant processes.