Regulatory T cell (Treg) therapy is a promising approach to amelioration of allograft rejection and promotion of organ transplant tolerance. However, the fate of infused Treg, and how this relates to their therapeutic efficacy using different immunosuppressive regimens is poorly understood. Our aim was to analyze the tissue distribution, persistence, replicative activity and phenotypic stability of autologous, donor antigen allo-reactive Treg (darTreg) in ATG-lymphodepleted, heart-allografted cynomolgus monkeys. darTreg were expanded ex vivo from flow-sorted, circulating Treg using activated donor B cells and infused post-transplant into recipients of MHC-mismatched heart allografts. Fluorochrome-labeled darTreg were identified and characterized in peripheral blood, lymphoid and non-lymphoid tissues and the graft by flow cytometric analysis. darTreg selectively suppressed autologous T cell responses to donor antigens in vitro. However, following their adoptive transfer after transplantation, graft surviortly after infusion. Nonpathogenic Torque Teno viruses (TTV) are highly prevalent in transplant recipients and associated with immunosuppression. Studies in kidney transplant patients have proposed assessment of TTV load for risk stratification of clinically overt graft rejection. The value of TTV quantification in the context of sub-clinical rejection has not been evaluated. In this prospective trial 307 consecutive kidney transplant recipients were subjected to per-protocol monitoring of plasma TTV. TTV was analysed in the context of protocol biopsies (n=82), scheduled one year posttransplantation. TTV load at the time of biopsy was lower in recipients with rejection (n=19; according to Banff, including borderline changes suspicious for acute T cell-mediated rejection) than those without rejection (n=63) whereby each log increase in TTV copies/mL decreased the risk for rejection by 9% (RR 0.91, 95%CI 0.85-0.97; P = 0.004). Development of chronic lesions (cg, cv, ci, ct, ah, ptcml) was associated with the number of days with a TTV load <1x106 copies/mL between month 3 and 12 posttransplant (β 0.07, 95%CI 0.01-0.14; P = 0.02). This trial demonstrates an association between TTV and subclinical graft rejection in kidney transplant recipients. A TTV load <1x106 copies/mL suggests sub-optimal immunosuppression (German Clinical Trials Registry DRKS00012335; Austrian Science Fund 604-B31).This trial demonstrates an association between TTV and subclinical graft rejection in kidney transplant recipients. A TTV load less then 1x106 copies/mL suggests sub-optimal immunosuppression (German Clinical Trials Registry DRKS00012335; Austrian Science Fund 604-B31). Risk factors, virologic parameters and outcomes associated with HHV-6 viremia in high-risk donor CMV-seropositive and recipient CMV-seronegative (D+R-) liver transplant recipients in the current era are incompletely defined. The study population consisted of patients in the preemptive therapy (PET) arm of a randomized, controlled trial of PET versus valganciclovir prophylaxis for CMV prevention in D+R- liver transplant recipients. Weekly blood samples through 100 days in the PET group were tested for HHV-6 viremia using a real-time quantitative PCR. Assessments included virologic characteristics and relationship with CMV, risk factors and impact of HHV-6 viremia with outcomes through 12 months post-transplant. HHV-6 viremia at any level developed in 42% (40/96). Older patient age (p=0.03), longer hospitalization (p=0.015), and ICU stay at transplantation (p=0.029) were significantly associated with high-grade viremia. Concurrent HHV-6 and CMV viremia was associated with earlier onset of HHV-6 viremia (p=0.004), higher HHV-6 AUC (p=0.043), and higher peak HHV-6 viral load (p=0.006) vs HHV-6 viremia alone. High-grade viremia was independently associated with biopsy-proven rejection within 12 months (p=0.045) post-transplant. Among D+R- liver transplant recipients receiving valganciclovir as PET, high-grade HHV-6 viremia was associated with increased age and critical-illness in ICU at time of transplant and was independently associated with allograft rejection.Among D+R- liver transplant recipients receiving valganciclovir as PET, high-grade HHV-6 viremia was associated with increased age and critical-illness in ICU at time of transplant and was independently associated with allograft rejection.Alcohol and cannabis use as a contraindication to organ transplantation is a controversial issue. SCR7 Until recently, patients in Canada with alcohol-associated liver disease (ALD) were required to demonstrate abstinence for 6 months in order to receive a liver transplant. There is no equivalent rule that is applied consistently for cannabis use. There is some evidence that alcohol and cannabis use disorder pretransplant could be associated with worse outcomes posttransplantation. However, early liver transplantation for patients with ALD in France and in the U.S. has led to challenges of the 6-month abstinence rule in Canada in the media. It has also resulted in several legal challenges arguing that the rule violates human rights laws regarding discrimination in the provision of medical services and that the rule is also unconstitutional (this challenge is still before the court). Recent legalization of cannabis use for adults in Canada has led to questions about the appropriateness of limiting transplant access based on cannabis use. The ethics committee of the Canadian Society of Transplantation (CST) was asked to provide an ethical analysis of cannabis and alcohol abstinence policies. Our conclusions were as follows neither cannabis use nor the 6-month abstinence rule for alcohol use should be an absolute contraindication to transplantation, and transplant could be offered to selected patients, further research should be conducted to ensure evidence-based policies; and the transplant community has a duty not to perpetuate stigma associated with alcohol and cannabis use disorders. The determination of antiretroviral drugs in hair is receiving considerable research interest to assess long-term adherence to antiretroviral therapy (ART). Currently in China, lamivudine, zidovudine, nevirapine, efavirenz, ritonavir, and lopinavir are combined as first- and second-line free therapy regimens and are recommended for people living with human immunodeficiency virus (HIV) (PLWH). Simultaneous determination of the six antiretroviral drugs in human hair is important for accurately and widely assessing long-term adherence in Chinese PLWH receiving different ART regimens. Six drugs were extracted from 10-mg hair samples incubated in methanol for 16 h at 37 °C and then analyzed by liquid chromatography with tandem mass spectrometry (LC-MS/MS) using a mobile phase of 95% methanol, with an electrospray ionization (ESI) source in multiple reaction monitoring and positive mode. The LC-ESI+-MS/MS method exhibited a linear range (R2 > 0.99) within 6-5000, 10-5000, 6-50000, 12-50000, 8-5000, and 8-12500 pg/mg for lamivudine, zidovudine, nevirapine, efavirenz, ritonavir, and lopinavir.