Induction of chronic polyarthritis in rabbits by hyperimmunization withEscherichia coliII. Immunohistologic findings in established arthritis

The objection of this paper was to investigate whether chronic polyarthritis in rabbits induced by hyperimmunization with Escherichia coli O: 14 produces immunohistologic changes in the arthritic tissues similar to rheumatoid arthritis (RA). The localization of IgG, C3, fibrinogen, rheumatoid factor-like substance (RFLS), IgM and IL-1 was assessed by immunofluorescence and immunoperoxidase techniques. The sensitizing antigen was examined by the immunoperoxidase method and radioimmunohistochemistry In addition, specimens were stained with monoclonal antibodies against t cells (CD4 and CD8). Concurrent localization of IgG and C3 was identified in the superficial layer of the inflamed synovium. At the periphery of lymphoid cell aggregation as follicles numerous IgG-containing plasma cells were found in the synovial villus and RFLS was detected within plasma cells in the synovium and lymph node. IL-1 was detected mainly in many macrophage-like cells and fibroblast-like cells. The sensitizing antigen was observed within the lumen of the blood vessel and its surrounding macrophages mainly accompanied by CD4+ T cells. We conclude that these findings are in agreement with the immunohistologic changes found in RA except for the localization of the antigen. The present data suggest that humoral and cellular immune mechanisms play a role in the development of E. coli-induced arthritis in rabbits. The presence of the sensitizing antigens including enterobacterial common antigen may help clarify the pathogenetic mechanism of RA in which the etiologic agents remain unknown.