[Innate immunity and transplantation]

Innate immunity is the first barrier against pathogen infection and has also the important function of activating the adaptive immunity. The receptors of innate immunity, such as toll-like receptors and other receptors, recognize as danger signals the molecular patterns of pathogens as well as those of endogenous molecules released by dying cells. The information is transmitted to adapter proteins that, through a chain of kinases that translate the signal to transcription factors regulating inflammatory genes. In the inflammatory milieu dendritic cells become mature, intercept the antigen and migrate to lymphoid organs where they present the antigen to naïve T cells. Complement also exerts an important role of bridge between innate and adaptive immunity. In donor-deceased kidney transplantation, the innate immunity is triggered in the donor by brain death and is aggravated by the cold ischemia and even more by reperfusion. Once activated, innate immunity produces a local inflammatory environment leading to dendritic cell maturation and complement activation. Dendritic cells present the alloantigen to T cells and induce their differentiation towards effector Th1 and Th17 while inhibiting Th2 and T regulatory cells. A main goal of the current research in transplantation is to obtain an immunological tolerance. Experimental studies showed the possibility of inducing operative tolerance in murine models and even in primates with the infusion of regulatory dendritic cells. However, there are no data with this technique in clinical transplantation.