PATHOGENESIS OF LACTOBACILLUS-CASEI-INDUCED POLYARTHRITIS IN LEWIS RATS .1. TIME-RELATED CHANGES IN HISTOPATHOLOGICAL SCORES AND HEMATOLOGY

Intraperitoneal injection of cell wall fragments from L. casei (ATCC 1 1578) induces an acute and a chronic inflammatory arthritis of the dis tal joints of LEW/N female rats. Histopathological changes in four dis tal joints and hematologic changes were analyzed on days 3, 10, 20, 30 , 40, 50 and 59. All joints were scored for changes in inflammation, p annus, cartilage and bone. The acute inflammatory response consisted o f fluid exudate, fibrin, neutrophils and some macrophages concentrated along the periosteum of the longer bones. The disease progressed with synovial fibroblast proliferation and infiltration of lymphocytes and macrophages. On day 10, cartilage changes were associated with pannus formation and subchondral fibrosis. Both localized bone resorption an d periosteal new bone formation were features of the chronic phase. Ly mphocytes were elevated above normal (p < 0.05) on day 3, 10, 20, 30 a nd 40; returning to the normal range on day 50 and 59. Neutrophils wer e elevated on days 10, 20, 30, 40 and 59. L. casei-induced polyarthrit is in Lewis rats appears to be a fibroblast-, macrophage-mediated dise ase with a prominent lymphoid component.