Extracorporeal photopheresis in solid organ transplantation
Despite the use of up-to-date immunosuppressive agents, graft rejection episodes are quite common and pose a serious threat to thousands of solid organ recipients. Continuous use of various combinations of immunosuppressants cause serious complications, such as arterial hypertension, post-transplant diabetes mellitus, renal failure, increased risk of infections, malignant neoplasms, etc. The attempts to achieve the desired or forced minimization of the graft immunosuppression are associated with the threat of its rejection, which makes it necessary to search for less toxic, non-medical, immunological, including cellular, management methods. One of the promising methods based on cell technology is extracorporeal photopheresis (ECP). ECP is a well-established second line therapy recommended for the prevention and treatment of refractory rejection of a heart transplant. ECP improves the pulmonary allograft functioning in patients with treatment resistant obliterating bronchiolitis syndrome. However, its value as a preventive method has not yet been established. ECP effectiveness for induction, maintenance, or anti-crisis therapy in transplantation of kidney, liver or other solid organs has been rather convincing, but the lack of randomized multicenter studies limits its use. The optimal ECP strategy has not been yet established. Nevertheless, current understanding of the pathophysiological and immunological aspects of ECP is sufficient to develop a standard methodology and technology for the procedure, as well as for a quality control system for ECP in kidney and liver transplant recipients. The review discusses possible mechanisms of the immunomodulating effect of ECP. ECP is being increasingly studied in prospective randomized trials with larger samples. This allows for an extension of its clinical indications with clear criteria, as well as for studying its multifactorial underlying immunomodulating mechanism of action. Further research is needed to identify biomarkers that could predict ECP effectiveness in solid organ transplantation.