[Pathological changes in cartilage of the knees in rabbits immunized with Escherichia coli 0:14]

Pathological changes in the articular cartilage were found in the knees of rabbits immunized with heat-killed Escherichia coli for 8-10 months at significantly higher rate (33.3%, 12 of 36 knees, p less than 0.05) than in those immunized for 1-4 months (17.6%, 6 of 34). Cartilage degeneration showed two types which were pannus invasion at the cartilage-synovial junction, and degeneration at superficial layer of the articular cartilage as seen in rheumatoid arthritis of human. Depositions of immunoglobulin were found in 10 out of 16 knees (62.5%) with the pannus invaded lesion and 5 out of 8 knees (75%) with the degenerated superficial layer of articular cartilage.