Differences in toll-like receptor ligand-induced cytokine concentrations before and after solid organ transplantation: A prospective, observational cohort study in a clinical setting.

Reliable methods to assess immune function after solid organ transplantation (SOT) are needed to guide dosing of immunosuppression. We hypothesized that toll-like receptor ligand-induced cytokine concentrations would decrease post-transplantation due to the use of immunosuppressive medication. Furthermore, we hypothesized that induced cytokine concentrations pre-transplantation would be higher in recipients with episodes of acute rejection post-transplantation due to underlying immunological dispositions. We aimed to investigate toll-like receptor ligand-induced cytokine concentrations by TruCulture©, a standardized immunoassay, in SOT recipients before and 3 months after SOT and explored associations with methylprednisolone-treated acute rejections. We conducted a prospective, observational cohort study including 123 participants (67 liver, 32 kidney and 24 lung transplant recipients). Whole blood was stimulated for 22 h with: (A) Lipopolysaccharide (LPS), (B) Resiquimod, (C) Polyinosinic:polycytidylic acid (Poly I:C) and (D) a blank control. Cytokine concentrations (TNF-α, IL-1ß, IL-6, IL-8, IL-10, IL-12p40, IL-17A, IFN-α and IFN-γ) were measured by Luminex. 30 participants developed methylprednisolone-treated acute rejection at a median of 9 days (IQR 5-17) post-SOT. We found that all induced cytokine concentrations decreased post-SOT except from LPS-induced and Poly I:C-induced IL-10. The induced cytokine concentration pre-transplantation did not differ in recipients with or without acute rejection. In conclusion, the induced cytokine concentrations decreased for all stimuli post-SOT, except the anti-inflammatory cytokine IL-10. Importantly, recipients developing early acute rejection did not differ in induced cytokine concentrations pre-SOT. Thus, the use of a standardized assay in SOT is feasible in a clinical setting and may provide important information on the immune function post-SOT.

Influenza in Liver and Kidney Transplant Recipients: Incidence and Outcomes.

Influenza is a common respiratory tract infection in solid organ transplant (SOT) recipients. We aimed to investigate the incidence, risk factors, and complications of influenza in a large cohort of kidney and liver transplant recipients over 10 consecutive seasons. We conducted a retrospective study, including 378 liver and 683 kidney transplant recipients who were transplanted from January 1, 2010, to October 1, 2019. The data on influenza were retrieved from MiBa, which is a nationwide database that contains all of the microbiology results in Denmark. Clinical data were retrieved from patient records. Incidence rates and cumulative incidences were calculated, and risk factors were investigated using time-updated Cox proportional hazards models. The cumulative incidence of influenza in the first 5 years posttransplantation was 6.3% (95% CI: 4.7 to 7.9%). Of the 84 influenza positive recipients, 63.1% had influenza A, 65.5% were treated with oseltamivir, 65.5% were hospitalized, and 16.7% developed pneumonia. There were no significant differences in outcomes when comparing patients with influenza A and B. We found no significant effect of same-season influenza vaccination, sex, age, or comorbidities on the risk of acquiring influenza. The incidence of influenza in kidney and liver recipients is high, and 65.5% of infected transplant recipients required hospitalization. We were not able to confirm a reduction in influenza incidence or in the risk of complications associated with vaccination. IMPORTANCE Influenza is a common respiratory virus in solid organ transplant recipients that may have severe complications, including pneumonia and hospitalization. This study investigates the incidence, risk factors, and complications of influenza in a Danish cohort of kidney and liver transplant recipients over 10 consecutive influenza seasons. The study shows a high incidence of influenza and a high frequency of both pneumonia and hospitalization. This emphasizes the importance of continuous focus on influenza in this vulnerable group. During the COVID-19 pandemic, the incidence of influenza has been low due to COVID-related restrictions, and immunity may have waned. However, as most countries have now opened up, the incidence of influenza is expected to be high this season.