Recruitment of Pathogenic T Cells to Synovial Tissues of Rats Injected Intraarticularly with Nonspecific Agents

To study a role for T cells in nonspecifically induced arthritis, rats were injected intraarticularly into ankle joints with mineral oils including 2,6,10,15,19,23-hexamethyltetracosane (squalene) and incomplete Freundʹs adjuvant. The results showed that moderate joint inflammation had developed by Day 6 after the nonspecific stimulation. This was then followed by induction of severe arthritis, reaching a peak on Day 21. Histologically, the early phase of arthritis was associated with edema of synovial tissues containing many polymorphs and monocytes/macrophages and the late phase of the joint inflammation with marked hyperplasia of synovial membrane with dense infiltration of CD5+ and αβ+ T cells. Depletion of αβ+ T cells by a monoclonal antibody against TCR αβ suppressed both induction and progression of the late phase of arthritis. Thus, pathogenic T cells appear to be recruited to joint tissues following nonspecific stimulation.