Linomide inhibits programmed cell death of peripheral T cells in vivo

Programmed cell death (PCD) is involved in the physiological regulation of lymphocyte turnover, as well in the antigen‐driven selection of T and B cells. Here it is shown that the immunomodulator linomide (quinoline‐3‐carboxamide) inhibits the apoptotic decay of peripheral T lymphocytes in response to three different stimuli. First, linomide reduces the superantigen‐mediated apoptosis and deletion of specific T lymphocytes of both the CD4⁺ and the CD8⁺ subsets without affecting other superantigen‐triggered phenomena such as T cell expansion and anergy. Second, linomide abolishes the T lymphopenia and inhibits PCD of splenic CD4⁺ and CD8⁺ T cells induced by exogenous glucocorticoids. This effect is restricted to peripheral T lymphocytes and does not concern thymocytes. Finally, linomide abolishes the development of lymphopenia that follows infection with vaccinia virus, while reducing PCD of CD4⁺ and CD8⁺ peripheral T cells. The anti‐apoptotic effect of linomide could account for its immunostimulatory properties and might be relevant to the treatment of immunodeficiencies associated with an increased apoptotic decay of T lymphocytes.