Papel de la fotoaféresis en el tratamiento del rechazo celular agudo refractario en trasplante renal

Extracorporeal Photopheresis, a Therapeutic Alternative for T cell-mediated Rejection in Renal Transplantation

T-cell mediated rejection (TCMR) in renal transplantation, although reduced by better immunosuppressants, still impacts graft survival. TCMR responds to methylprednisolone (MPL) in 60% to 70% of cases, with polyclonal anti-T-lymphocyte antibodies (ATGs) used for severe or corticoresistant cases. When ATG is contraindicated, extracorporeal photopheresis (ECP) may be an alternative. ECP involves treating immune cells with 8-methoxypsoralen and ultraviolet-A radiation before reinjection, with effect in various T-cell-mediated and autoimmune diseases. This study included two renal transplant recipients with severe TCMR. Patient 1's creatinine levels were 1.4 mg/dL baseline, 2.2 mg/dL at TCMR diagnosis, and 1.9 mg/dL at ECP initiation. Patient 2's levels were 1 mg/dL baseline, 1.8 mg/dL at diagnosis, and 1.42 mg/dL at ECP initiation. The THERAKOS CELLEX system was used for patient 1, and the OPTIA system was used for patient 2, both with methoxsalen. ECP is highlighted as a viable option for TCMR in renal transplantation when conventional treatments are unsuitable.

Extracorporeal Photopheresis Improves Graft Survival in a Full-Mismatch Rat Model of Kidney Transplantation

Extracorporeal photopheresis (ECP) is an immunomodulatory therapy based on the infusion of autologous cellular products exposed to ultraviolet light (UV) in the presence of a photosensitizer. The study evaluates the ECP efficacy as induction therapy in a full-mismatch kidney transplant rat model. Dark Agouti to Lewis (DA-L) kidney transplant model has been established. ECP product was obtained from Lewis rat recipients after DA kidney graft transplantation (Lew^DA). Leukocytes of those Lew^DA rats were exposed to 8-methoxy psoralen, and illuminated with UV-A. The ECP doses assessed were 10 × 10⁶ and 100 × 10⁶ cells/time point. Lewis recipients received seven ECP infusions. DA-L model was characterized by the appearance of donor-specific antibodies (DSA) and kidney function deterioration from day three after kidney transplant. The dysfunction progressed rapidly until graft loss (6.1 ± 0.5 days). Tacrolimus at 0.25 mg/kg prolonged rat survival until 11.4 ± 0.7 days (p = 0.0004). In this context, the application of leukocytes from LewDA sensitized rats accelerated the rejection (8.7 ± 0.45, p = 0.0012), whereas ECP product at high dose extended kidney graft survival until 26.3 ± 7.3 days, reducing class I and II DSA in surviving rats. ECP treatment increases kidney graft survival in full-mismatch rat model of acute rejection and is a suitable immunomodulatory therapy to be explored in kidney transplantation.

Infusion of Lymphocytes Treated With 8-Methoxypsoralen and Ultraviolet A Light Induces CD19+IL-10+ Regulatory B Cells and Promotes Skin Allograft Survival

Extracorporeal photopheresis (ECP) represents an alternative to immunosuppression as a means of reducing rejection after thoracic organ transplantation. The mechanism by which ECP exerts its protective effects, until now, has remained elusive. Infusion of ECP-treated splenic lymphocytes (PUVA-SP) can induce CD4⁺CD25^highFoxp3⁺ regulatory T cells. However, the regulatory effect of PUVA-SP on B cells remains poorly understood. In the present study, we measured IL-10 secretion from CD19⁺ B cells of peripheral blood mononuclear cells. Our results demonstrate that infusion of PUVA-SP (PUVA-BSP from BALB/c or PUVA-CSP from C57BL/6 mice), in the absence of an immunosuppressant, significantly promotes skin allograft survival. This effect was associated with upregulation of circulating regulatory B cells exhibiting preferential IL-10 secretion and a shift of cytokine profile from helper T cell type 1 to helper T cell type 2. Our results suggest that effective treatments involving infusion of PUVA-SP is likely related not only to the modulation of T cell and regulatory T cell functions but also to the function of B cell and regulatory B cells.