ABSTRACT
BACKGROUND: Binding of donor-specific antibodies (DSAs) to kidney allograft endothelial cells that does not activate the classic complement cascade can trigger the recruitment of innate immune effectors, including NK cells. Activated NK cells contribute to microvascular inflammation leading to chronic antibody-mediated rejection (AMR). Recipient NK cells can also trigger antibody-independent microvascular inflammation by sensing the absence of self HLA class I molecules ("missing self") on allograft endothelial cells. This translational study investigated whether the condition of missing self amplifies DSA-dependent NK cell activation to worsen chronic AMR. METHODS AND RESULTS: Among 1682 kidney transplant recipients who underwent an allograft biopsy at Lyon University Hospital between 2004 and 2017, 135 fulfilled the diagnostic criteria for AMR and were enrolled in the study. Patients with complement-fixing DSAs identified by a positive C3d binding assay (n=73, 54%) had a higher risk of transplant failure (P=0.002). Among the remaining patients with complement-independent chronic AMR (n=62, 46%), those in whom missing self was identified through donor and recipient genotyping exhibited worse allograft survival (P=0.02). In multivariable analysis, only proteinuria (HR: 7.24; P=0.01) and the presence of missing self (HR: 3.57; P=0.04) were independent predictors for transplant failure following diagnosis of chronic AMR. Cocultures of human NK cells and endothelial cells confirmed that addition of missing self to DSA-induced NK cell activation increased endothelial damage. CONCLUSIONS: The assessment of missing self at the time of diagnosis of chronic AMR identifies patients at higher risk for kidney transplant failure.
Subject(s)
Allografts/pathology , Complement Activation/physiology , Graft Rejection/etiology , Histocompatibility Antigens Class I/blood , Kidney Transplantation/adverse effects , Killer Cells, Natural/physiology , Adult , Allografts/immunology , Cell Culture Techniques , Complement C3d/metabolism , Endothelial Cells/physiology , Female , Graft Rejection/blood , Graft Rejection/pathology , Graft Survival , Humans , Killer Cells, Natural/pathology , Male , Middle Aged , Young AdultABSTRACT
With the COVID-19 pandemic and the ensuing barriers to the collection and transport of donor cells, it is often necessary to collect and cryopreserve grafts before initiation of transplantation conditioning. The effect on transplantation outcomes in nonmalignant disease is unknown. This analysis examined the effect of cryopreservation of related and unrelated donor grafts for transplantation for severe aplastic anemia in the United States during 2013 to 2019. Included are 52 recipients of cryopreserved grafts who were matched for age, donor type, and graft type to 194 recipients who received noncryopreserved grafts. Marginal Cox regression models were built to study the effect of cryopreservation and other risk factors associated with outcomes. We recorded higher 1-year rates of graft failure (hazard ratio [HR], 2.26; 95% confidence interval, 1.17 to 4.35; P = .01) and of 1-year overall mortality (HR, 3.13; 95% CI, 1.60 to 6.11; P = .0008) after transplantation of cryopreserved compared with noncryopreserved grafts, with adjustment for sex, performance score, comorbidity, cytomegalovirus serostatus, and ABO blood group match. The incidence of acute and chronic graft-versus-host disease did not differ between the 2 groups. Adjusted probabilities of 1-year survival were 73% (95% CI, 60% to 84%) in the cryopreserved graft group and 91% (95% CI, 86% to 94%) in the noncryopreserved graft group. These data support the use of noncryopreserved grafts whenever possible in patients with severe aplastic anemia.
Subject(s)
Anemia, Aplastic/therapy , Bone Marrow Transplantation/methods , Coronavirus Infections/epidemiology , Cryopreservation/methods , Graft Rejection/pathology , Graft vs Host Disease/pathology , Peripheral Blood Stem Cell Transplantation/methods , Pneumonia, Viral/epidemiology , Acute Disease , Adolescent , Adult , Aged , Anemia, Aplastic/immunology , Anemia, Aplastic/mortality , Anemia, Aplastic/pathology , COVID-19 , Child , Child, Preschool , Female , Graft Rejection/immunology , Graft Rejection/mortality , Graft vs Host Disease/immunology , Graft vs Host Disease/mortality , Histocompatibility Testing , Humans , Male , Middle Aged , Pandemics , Retrospective Studies , Siblings , Survival Analysis , Transplantation Conditioning/methods , United States/epidemiology , Unrelated DonorsABSTRACT
BACKGROUND: The impact of COVID-19 on heart transplant (HTx) recipients remains unclear, particularly in the early post-transplant period. METHODS: We share novel insights from our experience in five HTx patients with COVID-19 (three within 2 months post-transplant) from our institution at the epicenter of the pandemic. RESULTS: All five exhibited moderate (requiring hospitalization, n = 3) or severe (requiring ICU and/or mechanical ventilation, n = 2) illness. Both cases with severe illness were transplanted approximately 6 weeks before presentation and acquired COVID-19 through community spread. All five patients were on immunosuppressive therapy with mycophenolate mofetil (MMF) and tacrolimus, and three that were transplanted within the prior 2 months were additionally on prednisone. The two cases with severe illness had profound lymphopenia with markedly elevated C-reactive protein, procalcitonin, and ferritin. All had bilateral ground-glass opacities on chest imaging. MMF was discontinued in all five, and both severe cases received convalescent plasma. All three recent transplants underwent routine endomyocardial biopsies, revealing mild (n = 1) or no acute cellular rejection (n = 2), and no visible viral particles on electron microscopy. Within 30 days of admission, the two cases with severe illness remain hospitalized but have clinically improved, while the other three have been discharged. CONCLUSIONS: COVID-19 appears to negatively impact outcomes early after heart transplantation.