Lymphocyte subsets and mitogen induced proliferation in adjuvant arthritis. Part III. Numbers and functions of T lymphocytes in spleen.

The changes and the possible roles of splenic T lymphocyte subpopulations in high-responder Long-Evans (LE) rats and low-responder Sprague-Dawley (SD) rats with induced adjuvant arthritis (AA) were investigated. Total splenic T lymphocytes of both strains did not change significantly after the adjuvant injection. However, LE rats exhibited an increase in percentage of helper T cells and helper/suppressor T cell ratio, whereas SD rats expressed a decrease in the ratio with concomitant increase of suppressor T cells. This observation suggested that an imbalance of T lymphocyte ratio not only existed in the peripheral blood as reported by other investigators, but also existed in the spleen of rats with AA. In vitro measurement of phytohemagglutinin (PHA) responses of splenic T lymphocytes revealed an increased PHA response in LE but a markedly decreased PHA response in SD. Both LE and SD rats showed decreased response to concanavalin A (Con A) stimulation. We concluded that PHA response, as an index of helper T cell function, coincided with the development of AA and may be responsible for the immunoregulation of the disease. The increased proliferation of suppressor T cell in SD rats may also be significant in regulating the immune response to AA.