Early rheumatoid-like lesions in rabbits injected with foreign serum: relationship to localization of immune complexes in the lining tissues of joints and cellular content of synovial fluid.

Immune complex localization in joint tissues and white cell effusion into the joint space as well as synovial lesions are shown to occur in rabbits injected intravenously with bovine serum. Synovial lesions of one knee were found to be associated with immune complexes in joint tissues of the contralateral knee (because of the experimental design very few rabbits had both immunofluorescence and histology performed on the same joint). There was also a week correlation between moderate and gross synovial lesions and cellular effusions of the same joint. Cartilage proteoglycan depletion was seen in some injected animals and this was related to lining cell hyperplasia. Rabbits from different breeding colonies displayed different incidences of lesions suggesting an environmental or genetic influence on the development of rheumatoid-like lesions.