Antithymocytes globulins: Time to revisit its use in kidney transplantation?

T cell depletion by polyclonal antithymocyte globulins (ATG) has been used for many years in both organ and hematopoietic cell transplantation as an induction and rejection therapy. Nevertheless, its use remains largely empirical and many clinical questions, such as the determination of an individualized dose, therapeutic relevance of nondepletive effects, or prediction of long-term effects, are still unresolved. This review evaluates the evidence-based knowledge and the uncertainties concerning ATG, and suggests perspectives and opportunities for modern use of this old drug.