Various desensitization protocols were shown to enable successful living donor kidney transplantation across a positive complement‐dependent cytotoxicity crossmatch (CDCXM). Positive crossmatch ...transplantation, however, is less well established for deceased donor transplantation. We report a cohort of 68 deceased donor renal allograft recipients who, on the basis of broad sensitization (lymphocytotoxic panel reactivity ≥40%), were subjected to a protocol of peritransplant immunoadsorption (IA). Treatment consisted of a single session of immediate pretransplant IA (protein A) followed by posttransplant IA and antilymphocyte antibody therapy. Twenty‐one patients had a positive CDCXM, which could be rendered negative by pretransplant apheresis. Solid phase HLA antibody detection revealed preformed donor‐specific antibodies (DSA) in all 21 CDCXM‐positive and in 30 CDCXM‐negative recipients. At 5 years, overall graft survival, death‐censored graft survival and patient survival were 63%, 76% and 87%, respectively, without any differences between CDCXM‐positive, CDCXM‐negative/DSA‐positive and CDCXM‐negative/DSA‐negative recipients. Furthermore, groups did not differ regarding rates of antibody‐mediated rejection (24% vs. 30% vs. 24%, p = 0.84), cellular rejection (14% vs. 23% vs. 18%, p = 0.7) or allograft function (median 5‐year serum creatinine: 1.3 vs. 1.8 vs. 1.7 mg/dL, p = 0.62). Our results suggest that peritransplant IA is an effective strategy for rapid desensitization in deceased donor transplantation.
This study demonstrates successful transplantation of crossmatch‐positive deceased donor kidney allograft recipients using a protocol of peri‐transplant immunoadsorption for rapid alloantibody depletion immediately before transplant surgery.
Accumulation of inflammatory cells within capillaries is a common morphologic feature of humoral renal allograft rejection and is most easily appreciated if it occurs in glomeruli. The aim of our ...study was to determine the amount and composition of immune cells within glomeruli and peritubular capillaries (PTC) in cellular and humoral allograft rejection.
Immunofluorescent double‐labeling for CD31 and CD3 or CD68 was used for phenotyping and enumerating immune cells within glomeruli and PTC.
The major findings are: (1) accumulation of immune cells in PTC is far more common than it would be anticipated based on the assessment by conventional histology; (2) it is not the absolute number of immune cells accumulating within capillaries, but rather the composition of the intracapillary cell population that distinguishes humoral rejection from cellular rejection and (3) in C4d positive biopsies a predominantly monocytic cell population accumulates not only within glomeruli but also within PTC. The median value of monocyte/T‐cell ratio within PTC was 2.3 in C4d positive biopsies but only 1 (p = 0.0008) in C4d negative biopsies.
Given their prominent presence within capillaries and their extensive biological versatility monocytes might contribute to the capillary damage observed in acute and chronic allograft rejection.
Studies of transplant biopsies from kidneys with antibody‐mediated rejection revealed an excessive number of CD68+ monocytes within glomerular and peritubular capillaries, manifested by an elevated monocyte/T cell ratio in peritubular capillaries.
Humoral alloreactivity is well established to predict adverse allograft outcomes. However, in some recipients, alloantibodies may also occur in the absence of graft dysfunction. We evaluated if and ...how often complement‐ and noncomplement‐fixing alloantibodies are detectable in stable recipients and whether, in this context, they affect long‐term outcomes. Sera obtained from 164 kidney transplant recipients at 2, 6 and 12 months were evaluated by FlowPRA screening and single‐antigen testing for detection of IgG‐ or C4d‐fixing HLA panel reactivity and donor‐specific antibodies (DSA). Applying stringent criteria, we selected 34 patients with an uneventful 1‐year course (no graft dysfunction or rejection) and excellent graft function at 12 months estimated glomerular filtration rate (eGFR) ≥60 mL/min and proteinuria ≤0.5 g/24 h. Nine (27%) and 5 (15%) of these recipients tested positive by IgG and C4dFlowPRA screening, respectively. In five cases, DSA were identified. Frequencies of positive test results and DSA binding intensities were not significantly lower than those documented for patients who did not fulfill the above criteria. In recipients with an excellent 1‐year course, FlowPRA reactivity was not associated with lower eGFR or increased protein excretion during 68‐month median follow‐up. Our results suggest cautious interpretation of antibody monitoring in patients with normal‐functioning grafts.
This study demonstrates that, in kidney transplant recipients with excellent 1‐year graft performance, the occurrence of complement‐ and noncomplement‐fixing anti‐HLA alloreactivity may not be associated with adverse long‐term graft function, suggesting cautious interpretation of post‐transplant antibody monitoring in the absence of graft dysfunction.
Fc‐dependent effector mechanisms may contribute to antibody‐mediated rejection (ABMR), and distinct gene polymorphisms modifying the function of Fc gamma receptors (FcγRs) may influence the ...capability of donor‐specific antibodies (DSAs) to trigger inflammation. To evaluate the relevance of functional FcγR variants in late ABMR, 85 DSA‐positive kidney allograft recipients, who were recruited upon antibody screening of 741 prevalent patients, were genotyped for polymorphisms in FcγRIIA (FCGR2A‐H/R131; rs1801274), FcγRIIIA (FCGR3A‐V/F158; rs396991), and FcγRIIIB (FCGR3B‐neutrophil antigen 1 (NA1/NA2; rs35139848). Individuals with high‐affinity FCGR3A‐V158 alleles (V/V158 or V/F158) showed a higher rate (and extent) of peritubular capillaritis (ptc) in protocol biopsies than homozygous carriers of the lower‐affinity allele (ptc score ≥1: 53.6% vs 25.9%; P = .018). Associations were independent of C1q‐binding to DSA or capillary C4d. In parallel, there was a trend toward increased macrophage‐ and injury‐repair response–associated transcript subsets. Kidney function over 24 months, however, was not different. In support of a functional role of FcγRIIIA polymorphism, NK92 cells expressing FCGR3A‐V158 produced >2 times as much interferon gamma upon incubation with HLA antibody‐coated cells as those expressing FCGR3A‐F158. FcγRIIA and FcγRIIIB polymorphisms were not associated with allograft morphology. Our data suggest that the presence of high‐affinity FcγRIIIA variants may favor DSA‐triggered microcirculation inflammation.
This cross‐sectional study performed in kidney transplant recipients with donor‐specific antibodies suggests that the presence of high‐functional variants of Fc gamma receptor IIIA favors antibody‐triggered microcirculation inflammation independent of complement activation, supporting an important role of Fc receptor‐dependent mechanisms of injury.
The role of
Chlamydia pneumoniae in the pathogenesis of aortic aneurysm is controversial. We investigated the presence of
C. pneumoniae in tissue samples excised from patients and controls.
Aortic ...wall specimens were obtained from 17 patients with acute Stanford type A aortic dissection, 25 patients with thoracic aortic aneurysms (TAA) and 23 patients with abdominal aortic aneurysms (AAA). Eighty-three tissue samples of 73 control patients free of aortic disease were obtained either at surgery or autopsy. The presence of
Chlamydia subspecies DNA (sequences specific for all known
Chlamydiaceae) and DNA of
C. pneumoniae,
C. trachomatis and
C. psittaci were assessed by a validated highly sensitive and specific real time polymerase chain reaction (PCR) analysis. Atherosclerotic risk factors were assessed in all patients.
We failed to detect
C. pneumoniae and
C. psittaci-DNA in any of the 148 vessel specimens.
C. trachomatis-DNA was detected in 1/65 patients and in none of 83 controls (
P=0.43).
Chlamydia subspecies DNA was found in samples of eight cases and in one control (
P=0.01), however, no significant differences were found between the subgroups aortic dissection (
P=0.09), TAA (
P=0.99) and AAA (
P=0.15) and respective controls.
C. pneumoniae does not play a clinically relevant role in acute and chronic aortic disease. The impact of other organisms of the family
Chlamydiaceae needs further evaluation.
Recent studies indicate that not all low-level donor-specific human leukocyte antigen (HLA) antibodies (HLA-DSA) (i.e., positive by solid-phase assays, negative by complement-dependent ...cytotoxic-crossmatch) have a detrimental clinical impact. The aim of this study was to investigate whether the pretransplant C4d-fixing capability allows distinguishing harmful from presumably clinically irrelevant HLA-DSA.
We retrospectively investigated 64 patients with low-level HLA-DSA detected by single-antigen flow beads (SAFB). Thirty-four of 64 patients (53%) experienced early antibody-mediated rejection (AMR), whereas 30 patients (47%) did not. HLA-DSA characteristics (i.e., number, class, and strength), frequency of retransplants, and immunosuppressive regimens were not different in these two groups. Pretransplant sera were reanalyzed using a modified SAFB assay measuring C4d fixation induced by HLA antibodies.
C4d-fixing HLA-DSA were observed in 11 of 64 patients (17%). AMR occurred in 6 of 11 patients (55%) with C4d-fixing HLA-DSA and in 28 of 53 patients (53%) without C4d-fixing HLA-DSA (P=1.0). Positive C4d staining in peritubular capillaries was detected in 6 of 11 patients (55%) with C4d-fixing HLA-DSA and in 21 of 53 patients (40%) without C4d-fixing HLA-DSA (P=0.50).
The pretransplant capability of low-level HLA-DSA to trigger C4d fixation in vitro is not predictive for early AMR or C4d deposition in peritubular capillaries in vivo. This argues against pretransplant C4d SAFB testing to define the clinical relevance of low-level HLA-DSA.
ABO-incompatible kidney transplantation performed after desensitization with antigen-specific immunoadsorption (IA) results in good outcomes. However, a unique single-use IA device is required, which ...creates high costs.
From August 2005 to August 2010, 19 patients were desensitized for ABO-incompatible living donor kidney transplantation. Six patients treated with a single-use antigen-specific IA device and 12 patients treated with a reusable non-antigen-specific IA device were analyzed.
Six patients who received antigen-specific IA had a median of 5 IA treatments and 12 patients with non-antigen-specific IA had a median of 6 IA treatments preoperatively. Median average titer drop in Coombs technique was 1.2 in antigen-specific IA and 1.7 in non-antigen-specific IA. In two patients with antigen-specific IA and four patients with non-antigen-specific IA, additional plasmapheresis treatments were necessary for recipient desensitization. Despite six treatments with antigen-specific IA and 12 plasmapheresis treatments, one patient with a starting isoagglutinin titer of 1:1024 (Coombs) could not be transplanted. The 18-month graft survival rate for the 17 ABO-incompatible living donor kidney transplants was 100%. One male recipient who was desensitized with antigen-specific IA died 44 months after transplantation from sudden cardiac death with a serum creatinine of 1.2 mg/dL. At last follow-up, a median of 13 months after transplantation, median serum creatinine for 16 patients was 1.5 mg/dL, median glomerular filtration rate as estimated by the modification of diet in renal disease formula 54 mL/min/1.73 m, and median urinary protein-to-creatinine ratio 0.1, with no differences between treatments.
A reusable non-antigen-specific IA device allows high number of treatments at reasonable cost, and at the same time might deplete human leukocyte antigen-alloantibodies.
The classic pathway (CP) of complement is believed to significantly contribute to alloantibody‐mediated transplant injury, and targeted complement inhibition is currently considered to be a promising ...approach for preventing rejection. Here, we investigated the mode of action and efficacy of the humanized anti‐C1s monoclonal antibody TNT009 and its parental mouse variant, TNT003, in preclinical in vitro models of HLA antibody–triggered CP activation. In flow cytometric assays, we measured the attachment of C1 subcomponents and C4/C3 split products (C4b/d, C3b/d) to HLA antigen–coated flow beads or HLA‐mismatched aortic endothelial cells and splenic lymphocytes. Anti‐C1s antibodies profoundly inhibited C3 activation at concentrations >20 μg/mL, in both solid phase and cellular assays. While C4 activation was also prevented, this was not the case for C1 subcomponent attachment. Analysis of serum samples obtained from 68 sensitized transplant candidates revealed that the potency of inhibition was related to the extent of baseline CP activation. This study demonstrates that anti‐C1s antibodies TNT009 and TNT003 are highly effective in blocking HLA antibody–triggered complement activation downstream of C1. Our results provide the foundation for clinical studies designed to investigate the potential of TNT009 in the treatment or prevention of complement‐mediated tissue injury in sensitized transplant recipients.
This study demonstrates the mode of action and inhibition efficacy of the novel humanized anti‐C1s antibody TNT009 and its parental mouse variant TNT003 on anti‐HLA antibody‐triggered complement deposition in cellular and solid‐phase flow cytometric assays.
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