A bit of antithymocyte globulin can take you a long way!

Abstract

The success of allogeneic hematopoietic SCT (allo-SCT) owes much to the improvements in immunosuppressive regimens that prevent GVHD. For the past 25 years, the mainstay of immunosuppression has been the calcineurin antagonists CSA and tacrolimus. However, their immunosuppressive effects can be unpredictable. The so-called ‘T-cell-depleting’ antibodies such as antilymphocyte or antithymocyte globulins (ATGs) have been used for decades. The general common belief is that ATG efficacy relies on its potent capacity to deplete T lymphocytes of the graft. However, an ever-growing body of more recent data suggested that ATG affects not only the T lymphocytes, but also other key cells involved in the immune reaction. Indeed, the immunosuppressive activity of ATG has been thought to result primarily from the depletion of peripheral T lymphocytes from the circulating pool through complement-dependent lysis or activation-associated apoptosis. Other potential mechanisms of action include the modulation of surface adhesion molecules or chemokine receptor expression. In addition to their T-cell-depleting properties, ATGs can modulate the immune response by affecting or interfering with the function of different immune effectors such as B lymphocytes, regulatory T lymphocytes, natural killer-T lymphocytes and DCs.1