Variation of lymphocytes in peripheral blood and bone marrow in collagen-induced arthritis

Collagen-induced arthritis (CIA) was found to be useful as an animal model to investigate the mechanism by which rheumatoid arthritis is developed. We therefore studied variations of T and B lymphocytes in peripheral blood and bone marrow in order to ascertain the importance of T and B lymphocytes in the development of CIA. T lymphocyte, which is considered to be associated with the onset and deterioration of CIA, was not changed during the course of CIA, whereas B lymphocyte, which produces anti-type II collagen antibody regarded as an indispensable factor in CIA induction, was significantly decreased in peripheral blood and bone marrow at 10 days after the 2nd immunization when arthritis was able to be detected. In bone marrow, although two cell populations of Ly5/B220-positive cells were detected, only the cell population with lower fluorescence intensity was decreased transiently. These results suggest that B lymphocyte in both bone marrow and peripheral blood is intimately involved in the course of CIA.