Células T reguladoras y tolerancia en trasplante: Efecto de la inmunosupresión farmacológica

The poor long-term graft survival rate counteracts the important advance that transplantation is for end-stage disease patients. This is mainly due to the use of immunosuppressants that nonspecifically inhibit the immune response to avoid graft rejection but that bring a number of adverse effects leading to chronic rejection. Thus, the major goal in transplant medicine is to reach an absence of immune response towards donor alloantigens without the need of long-term immunosuppressant drugs. In the last years, regulatory T cells, mainly those with a CD4+CD25highFOXP3+ phenotype (named as Treg cells), have demonstrated an inhibitory effect on immune responses against donor alloantigens. As a consequence, they are a potential tool in the development of transplant tolerance in vivo. Most of the evidence comes from experimental models, although recent works address the role of Treg cells in the clinical setting of transplantation. In such a setting, the coexistence of immunosuppression in almost 100% of the patients is an essential factor to consider. Recent findings show that different drugs favour the induction and/or maintenance of Treg cells in transplant recipients. Among them, mTOR inhibitors seem to promote the development of Treg cells at present. Next strategies include the ex vivo stimulation of sorted Treg cells with donor alloantigens or the transfection of alloreactive CD4+CD25- cells with FOXP3.