**5. Conclusion**

We summarize in a Figure the different factors and critical steps involved in CD4+ T cell reconstitution after depletion by ATG (Figure 1). Overall, the aim of this review was to report our experience on the identification of biomarkers (CD4+ T cell lymphopenia after ATG and TREC levels at the time of transplantation) predicting transplantation-related complications (mainly atherosclerosis and cancer occurrence), and to propose to use these biomarkers in patient follow up and/or in immunosuppressive strategy design. Furthermore, we propose other "tracks" to improve the clinical relevance of these biomarkers, as well as to understand their implications in the occurrence of immunosuppression-associated complications. The efficacy of these identified biomarkers should be tested and validated in prospective clinical trials in order to select the appropriate immunosuppressive strategy. In the future, one could imagine that these biomarkers may help physicians to manage risks of cancers and cardiovascular diseases in renal transplant recipients.
