Abstract
Adjuvant-induced arthritis (AA) can be produced by a single injection of Freund's complete adjuvant (FCA) containing Mycobacterium. Various bacteria, their cell walls and their peptidoglycans can be substituted for Mycobacterium in FCA. Asynthetic adjuvant, N-acetylmuramyl-L-Ala-D-isoGln (MDP) also produced polyarthritis indistinguishable from AA in terms of clinical course and chronic granulomatous lessions around joints. MDP produced very severe arthritis in euthymic rats but not in athymic nude rats. We have not yet succeeded in reconstituting the disease susceptibility of nude rats by thymus cells or lymphoid cells. All of the germfree (GF) F344 rats developed severe AA whereas conventional and specific pathogen free (SPF) rats developed the disease with low incidence and less severity. When GF rats were associated orally with E. coli and 4 weeks later were injected with FCA, E. coli-associated GF rats developed very mild disease comparable to that of SPF rats. Lactobacilli-associated GF rats developed much severe disease than that of GF rats. These findings suggested that (i) thymus plays an important role in pro-moting the development of AA; (ii) bacterial flora must exert some effects on the development of AA.
