The effects of T cells and their products on in vitro healing of epitenon cell microwounds.

The purpose of the present investigation was to study the activity and behaviour of rat epitenon cells cultured in the presence of activated helper/inducer T lymphocytes and T-cell-derived cytokines interleukin-1 (IL-1), IL-2, transforming growth factor-beta (TGF-beta) and interferon-gamma (IFN-gamma). We measured the speed of healing of microwounded monolayers of epitenon cells as well as intercellular adhesion, cell proliferation and fibronectin production. The speed of monolayer healing was increased in the presence of activated CD4+ T lymphocytes and cytokines: TGF-beta > IL-2 > IL-1 > IFN-gamma. TGF-beta and IL-2 were also found to promote cell-cell adhesion; other cytokines had a minor effect. IL-2, IL-1 and IFN-gamma promoted [3H]thymidine incorporation in epitenon cells whereas TGF-beta had an inhibitory effect. Fibronectin production was studied with immunofluorescence staining methods. Activated CD4+ T lymphocytes and TGF-beta stimulated the deposition of fibronectin whereas other cytokines did not have a significant effect. Our results suggest that activated T lymphocytes and T-cell-derived cytokines, especially IL-2 and TGF-beta play a crucial role in the regulation of epitenon cell proliferation, adhesion and extracellular matrix production during in vitro microwound healing. As epitenon cells are the main cell type participating in tendon repair, factors regulating their activity may find application in clinical practice.