Profiles of B-cell subsets in immunologically stable renal allograft recipients and end-stage renal disease patients

BackgroundPost-transplantation pharmacotherapies typically employ combinations of immunosuppressive agents that have been designed for targeted inhibition of T-cells and T-cell subsets. Studies of acute and chronic effects of clinically employed immunosuppressive agents on B-cells and B-cell subsets are significantly fewer in number and warrant further investigation. Accordingly, the goal of the present cross-sectional study is to functionally evaluate differences of B-cell subsets in patients with end-stage renal disease (ESRD) and immunologically stable renal transplant patients.Patients and methodsOf 103 patients who underwent renal transplantation, 73 patients were immunologically stable without rejection or infection. Among them, 34 patients were one-year post-transplantation, and 39 patients were five-year post-transplantation. The study also included 35 ESRD patients and 36 healthy volunteers. Flow cytometry identified B-cell subsets in the study groups.ResultsRenal allograft recipients had reduced percentages of total B-cells (CD19+) and regulatory B-cells (B_reg) (CD38^highCD27 + CD24+) compared with healthy controls. The percentage of transitional B-cells (IgM + CD38^highCD24^high) and marginal zone (MZ) B-cells (IgD-CD27+) was reduced in transplant recipients compared with patients with ESRD and healthy volunteers. The highest percentage of plasma cells (PCs) (CD38^highCD27 + CD24-) was in patients with ESRD. In five-year post-transplantation group, CD38^lowCD21- B-cells increased when compared with the other groups. Healthy volunteers and patients with ESRD had fewer unswitched memory (UM) B-cells (IgM + IgD + CD38^lowCD27+), and increased isotype switched memory (ISM) B-cells (IgM-IgD-CD38^lowCD27+). There was no difference in the percentage of naïve B-cells (IgD + CD27-) among diverse groups.ConclusionsThe percentages of the total, transitional, B_reg, PCs, MZ, and UM B-cell subsets in immunologically stable renal allograft recipients were significantly different from healthy controls. However, B-cell subsets in patients with ESRD were minimally different with immunologically stable renal allograft recipients.     

The influence of CTLA‐4 single nucleotide polymorphisms on acute kidney allograft rejection in Turkish patients

Cytotoxic T‐lymphocyte antigen‐4 (CTLA‐4) is a cell surface protein, which down‐regulates the immune response at CTLA‐4/CD28/B7 pathway. We aimed to investigate the influence of the ?318C/T, +49A/G, ?1661A/G and CT60A/G, and CTLA‐4 gene polymorphisms on acute rejection of kidney allograft in Turkish patients. The study design was a case–control study that consists of three groups: Group 1 (n = 34) represented the kidney transplant (Ktx) recipients who experienced acute rejection, Group 2 (n = 47) was randomly assigned Ktx recipients without acute rejection, and Group 3 (n = 50) consisting of healthy volunteers to evaluate the normal genomic distribution. The polymerase chain reaction–restriction fragment length polymorphism technique was used to determine the polymorphisms. Genotype and allele frequencies among three groups denoted similar distributions for +49A/G, ?1661A/G, and CT60A/G. Conversely, ?318C/T genotype was three times more frequent in the acute rejection group than in the non‐rejection group (OR = 3.45; 95%CI = 1.18–10.1, p = 0.015) and two times more frequent than the healthy control group (OR = 2.45; 95% CI = 0.98 – 6.11, p = 0.047). Additionally, having a T allele at ?318 position was significantly associated with acute rejection (0.147 vs. 0.043, OR = 3.45; 95% CI = 1.13–10.56, p = 0.02). 318C/T gene polymorphism and T allelic variant were found to be associated with increased acute rejection risk in Turkish kidney allograft recipients.     

CMV‐infected kidney grafts drive the expansion of blood‐borne CMV‐specific T cells restricted by shared class I HLA molecules via presentation on donor cells

We aimed to determine the role of cytomegalovirus (CMV)‐infected donor cells in the development of a CMV‐specific immune response in kidney transplant recipients. We assessed the CMV pp65‐specific immune response by using interferon‐? ELISPOT and dextramers in peripheral blood mononuclear cells from 115 recipients (D+R? 31, D+R + 44, D?R + 40) late after transplantation (mean 59 ± 42 months). Receiving a kidney from a D+ donor resulted in a higher number of IFN‐?‐producing anti‐CMV T cells (P = .004). This effect disappeared with the absence of shared HLA class I specificities between donors and recipients (P = .430). To confirm the role of donor cells in stimulating the expansion of newly developed CMV‐specific CD8⁺ T cells after transplantation, we compared the number of HLA‐A2–restricted CMV‐specific CD8⁺ T cells in primo‐infected recipients who received an HLA‐A2 or non–HLA‐A2 graft. The median of anti‐CMV pp65 T cells restricted by HLA‐A2 was very low for patients who received a non–HLA‐A2 graft vs an HLA‐A2 graft (300 [0‐14638] vs. 17972 [222‐85594] anti‐CMV pp65 CD8⁺ T cells/million CD8⁺ T cells, P = .001). This adds new evidence that CMV‐infected kidney donor cells present CMV peptides and drive an inflation of memory CMV‐specific CD8⁺ T cells, likely because of frequent CMV replications within the graft.     

Value of a flow cytometry cross‐match in the setting of a negative complement‐dependent cytotoxicity cross‐match in heart transplant recipients

Complement‐dependent cytotoxicity cross‐match (CDCXM) is used for evaluation of preformed HLA‐specific antibodies in patients undergoing heart transplantation. Flow cytometry cross‐match (FCXM) is a more sensitive assay and used with increasing frequency. To determine the clinical relevance of a positive FCXM in the context of negative CDCXM in heart transplantation, the United Network for Organ Sharing (UNOS) database was analyzed. Kaplan‐Meier analysis and Cox proportional hazard modeling were used to assess graft survival for three different patient cohorts defined by cross‐match results: T‐cell and B‐cell CDCXM+ (“CDCXM+” cohort), CDCXM? but T‐cell and/or B‐cell FCXM+ (“FCXM+” cohort), and T‐cell/B‐cell CDCXM? and FCXM‐ (“XM?” cohort). During the study period, 2558 patients met inclusion criteria (10.7% CDCXM+, 18.8% FCXM+, 65.5% XM?). CDCXM+ patients had significantly decreased graft survival compared to FCXM+ and XM? cohorts (P = .003 and <.001, respectively). CDCXM? and FCXM+ patients did not have decreased graft survival compared to XM? patients (P = .09). In multivariate analysis, only CDCXM+ was associated with decreased graft survival (HR 1.22, 95% CI 1.01‐1.49). In conclusion, positive FCXM in the context of negative CDCXM does not confer increased risk of graft failure. Further study is needed to understand implications of CDCXM and FCXM testing in heart transplant recipients.     

Influence of preoperative anti‐HLA antibodies on short‐ and long‐term graft survival in recipients with or without rituximab treatment

We investigated the relationship between preoperative anti‐HLA antibodies (donor‐specific antibody, DSA) and the graft survival rate in recipients who had or had not received rituximab (Rit) treatment. The subjects were categorized into four groups as follows: DSA+Rit?, n = 39; DSA?Rit?, n = 121; DSA+Rit+, n = 74; and DSA?Rit+, n = 47. We examined the influence of preoperative DSA on the incidence of graft rejection and the survival rate of recipients who had or who had not received rituximab before transplantation. The 6‐month acute rejection rates based on graft biopsies were 39%, 19%, 15%, and 0% for the DSA+Rit?, DSA?Rit?, DSA+Rit+, and DSA?Rit+ groups. The rates of chronic antibody‐mediated rejection after more than 6 months were 50%, 22%, 18%, and 0%. The 5‐year graft survival rate was significantly lower in the DSA+Rit? group (84%) than in the other groups (95% for DSA?Rit?, 98% for DSA+Rit+, and 91% for DSA?Rit+). The rate of the appearance of de novo anti‐HLA antibodies was higher in the groups that did not receive rituximab treatment. The rate of graft loss associated with chronic antibody‐mediated rejection was also higher in the DSA+Rit? group than in the other groups (P = 0.01). The presence of DSA and the administration of rituximab had strong impacts on not only short‐term graft rejection, but also long‐term graft rejection and its association with the graft survival time.     

Outcomes and risk stratification for late antibody‐mediated rejection in recipients of ABO‐incompatible kidney transplants: a retrospective study

The required intensity of monitoring for antibody‐mediated rejection (AMR) after of ABO‐incompatible (ABOi) kidney transplantation is not clearly formulized. We retrospectively evaluated a single‐center cohort of 115 ABO‐incompatible (ABOi) kidney transplant recipients, of which 32% were also HLA incompatible (ABOi/HLAi) with their donors. We used an adjusted negative binomial model to evaluate risk factors for late AMR. Using this model, we risk‐stratified patients into high‐ and low‐risk groups for the development of late AMR; 26% of patients had at least one AMR episode; 49% of AMR episodes occurred within 30‐days after transplant and were considered early AMR. Patients with an early AMR episode had a 5.5‐fold greater incidence of developing late AMR [IRR = 5.5, (95% CI: 1.5–19.3), P = 0.01]. ABOi/HLAi recipients trended toward increased late AMR risk [IRR = 1.9, (95% CI: 0.5–6.6), P = 0.3]. High‐risk recipients (those with an early AMR or those who were ABOi/HLAi) had a sixfold increased incidence of late AMR [IRR = 6.3, (95% CI: 1.6–24.6), P = 0.008] versus low‐risk recipients. The overall incidence of late AMR was 20.8% vs. 1.5% in low‐risk recipients. Changes in anti‐A/B titer did not correlate with late AMR (IRR = 0.9 per log titer increase, P = 0.7). This risk‐stratification scheme uses information available within 30 days of ABOi transplantation to determine risk for late AMR and can help direct longitudinal follow‐up for individual patients.     

Association of TNF‐α, TGF‐β1, IL‐10, IL‐6, and IFN‐γ gene polymorphism with acute rejection and infection in lung transplant recipients

Infection and rejection are common complications faced by lung transplant recipients (LTRs) and have become major impediments to long‐term survival. Cytokines may play an important role in the development of these complications. In this study, we explored the correlation between TNF‐α (?308 A/G), TGF‐β1 (+869 T/C, +915 G/C), IL‐10 (?592 C/A, ?819 T/C, ?1082 G/A), IL‐6 (?174 G/C), and IFN‐γ (+874 T/A) gene polymorphisms and the incidence of acute rejection and infection. Transplant outcomes were reviewed in a retrospective cohort of 113 LTRs from a single center between December 2004 and November 2012. Cytokine polymorphisms were measured using sequence‐specific primer‐based PCR. HLA typing was performed for the donors and recipients. We found that the LTRs with the IL‐10 ?819 CC and ?592 CC genotypes had a significantly decreased risk of infection (p = 0.017, OR = 0.177, 95% CI = 0.04–0.85). However, we found no significant association between cytokine polymorphisms and acute rejection. Furthermore, the data revealed that the occurrence of acute rejection was strongly associated with infection episodes (χ² = 8.5256, p < 0.01). These results suggest that LTRs possessing the IL‐10 ?819 CC and ?592 CC genotype may be protected from the occurrence of infection. Our results demonstrated that infection is an important cause of acute rejection for LTRs.     

Dynamic changes of B‐cell compartments in kidney transplantation: lack of transitional B cells is associated with allograft rejection

B cells play an important role in the immune responses which affect the outcomes of kidney allografts. Dynamic changes of B‐cell compartments in clinical kidney transplantation are still poorly understood. B‐cell subsets were prospectively monitored using flow cytometry for 1 year in 98 kidney transplant recipients. Data were correlated with immunosuppression and clinical outcomes. An increase in the total population of B lymphocytes was observed during the first week after transplantation. The level of IgM^highCD38^highCD24^high transitional B cells reduced significantly up until the third month, with partial repopulation in the first year. Lower numbers of transitional B cells in the third month were associated with higher risk of graft rejection. IgM⁺IgD⁺CD27^? naive B cells did not change within follow‐up. IgM⁺CD27⁺ nonswitched memory B cells and IgM^?CD27⁺ switched memory B cells increased on post‐operative day 7. IgM^?CD38^highCD27^high plasmablasts showed similar kinetics during the first post‐transplant year, similar to transitional B cells. In conclusion, sensitized kidney transplant recipients as well as those with either acute or chronic rejection within the first post‐transplant year exhibited lower levels of transitional B cells. Therefore, these data further support the hypothesis that transitional B cells have a protective role in kidney transplantation.     

Renal Transplantation With Final Allocation Based on the Virtual Crossmatch

Solid phase immunoassays (SPI) are now routinely used to detect HLA antibodies. However, the flow cytometric crossmatch (FCXM) remains the established method for assessing final donor–recipient compatibility. Since 2005 we have followed a protocol whereby the final allocation decision for renal transplantation is based on SPI (not the FCXM). Here we report long‐term graft outcomes for 508 consecutive kidney transplants using this protocol. All recipients were negative for donor‐specific antibody by SPI. Primary outcomes are graft survival and incidence of acute rejection within 1 year (AR <1 year) for FCXM+ (n = 54) and FCXM? (n = 454) recipients. Median follow‐up is 7.1 years. FCXM+ recipients were significantly different from FCXM? recipients for the following risk factors: living donor (24% vs. 39%, p = 0.03), duration of dialysis (31.0 months vs. 13.5 months, p = 0.008), retransplants (17% vs. 7.3%, p = 0.04), % sensitized (63% vs. 19%, p = 0.001), and PRA >80% (20% vs. 4.8%, p = 0.001). Despite these differences, 5‐year actual graft survival rates are 87% and 84%, respectively. AR <1 year occurred in 13% FCXM+ and 12% FCXM? recipients. Crossmatch status was not associated with graft outcomes in any univariate or multivariate model. Renal transplantation can be performed successfully, using SPI as the definitive test for donor–recipient compatibility.     

Excessive immunosuppression as a potential cause of poor survival in simultaneous liver/kidney transplantation for hepatitis C

Appropriate recipient selection of simultaneous liver/kidney transplantation (SLKT) remains controversial. In particular, data on liver graft survival in hepatitis C virus‐infected (HCV+) SLKT recipients are lacking. We conducted a single‐center, retrospective study of HCV+ SLKT recipients (N = 25) in comparison with HCV? SLKT (N = 26) and HCV+ liver transplantation alone (LTA, N = 296). Despite backgrounds of HCV+ and HCV? SLKT being similar, HCV+ SLKT demonstrated significantly impaired 5‐year liver graft survival of 35% (HCV? SLKT, 79%, P = 0.004). Compared with HCV+ LTA, induction immunosuppression was more frequently used in HCV+ SLKT. Five‐year liver graft survival rate for HCV+ SLKT was significantly lower than that for LTA (35% vs. 74%, respectively, P < 0.001). Adjusted hazard ratio of liver graft loss in HCV+ SLKT was 4.9 (95% confidence interval 2.0–12.1, P = 0.001). HCV+ SLKT recipients were more likely to succumb to recurrent HCV and sepsis compared with LTA (32% vs. 8.8%, P < 0.001 and 24% vs. 8.8%, P = 0.030, respectively). Ten HCV+ SLKT recipients underwent anti‐HCV therapy for recurrent HCV; only 1 achieved sustained virological response. HCV+ SLKT is associated with significantly decreased long‐term prognosis compared with HCV? SLKT and HCV+ LTA.     

Graft and patient outcomes of zero‐human leucocyte‐antigen‐mismatched deceased and live donor kidney transplant recipients

Greater compatibility of human leucocyte antigen (HLA) alleles between kidney donors and recipients may lead to improved graft outcomes. This study aimed to compare the incidence of acute rejection and graft failure in zero‐HLA‐mismatched recipients of living‐related (LD) and deceased donor (DD) kidney transplants. Using data from the Australia and New Zealand Dialysis and Transplant Registry, we compared the risk of any acute rejection and biopsy‐proven acute rejection (BPAR) and graft failure in recipients of zero‐HLA‐mismatched kidneys between LD and DD using logistic and Cox regression models. Of the 931 zero‐HLA‐mismatched recipients transplanted between 1990 and 2012, 19 (2.0%) received kidneys from monozygotic/dizygotic twins (twin), 500 (53.7%) from nontwin LD and 412 (44.3%) from DD. Twin kidney transplant recipients did not experience rejection. Compared to DD transplant recipients, the risk of any acute rejection (adjusted odds ratio 0.52, 95%CI 0.34–0.79, P = 0.002) and overall graft failure (adjusted hazard ratio 0.55, 95%CI 0.41–0.73, P < 0.001) was significantly lower in LD recipients independent of initial immunosuppression, but not for BPAR (adjusted odds ratio 0.52, 95%CI 0.16–1.64, P = 0.263). Zero‐HLA‐mismatched DD kidney transplant recipients have a significantly higher risk of any acute rejection episodes and graft loss compared to zero‐HLA‐mismatched LD kidney transplant recipients. A cautious and careful approach in reducing immunosuppression appears to be warranted in this group of transplant recipients.     

A prospective longitudinal analysis of cytomegalovirus (CMV)‐specific CD4+ and CD8+ T cells in kidney allograft recipients at risk of CMV infection

Cytomegalovirus (CMV)‐specific cellular immunity is essential in controlling CMV infection after transplantation. We investigated whether CMV‐specific T cell levels predict CMV DNAemia after kidney transplantation. Using cytokine‐flow cytometry, we enumerated interferon‐γ producing CMV‐specific CD4+ and CD8+ T cells at serial time points among CMV‐mismatched (D+/R?) and seropositive (R+) kidney recipients who received 3 months of valganciclovir prophylaxis. Among 44 patients, eight (18%) developed CMV DNAemia at a mean (±SD) time of 151 (±33) days after transplantation, including two (5%) with CMV syndrome and three (7%) with tissue‐invasive CMV disease. Cox proportional hazards regression analysis showed that CMV mismatch (D+/R?) status (HR: 13, 95% CI: 1.6–106.4; P = 0.02) and diabetes mellitus (HR: 5.6; 95%CI: 1.1–27.9; P = 0.03) were significantly associated with CMV DNAemia. In contrast, the percentage or change‐over‐time in CMV‐specific CD4+ [pp65 (P = 0.45), or CMV lysate (P = 0.22)] and CD8+ [pp65 (P = 0.43), or IE‐1 (P = 0.37)] T cells were not significantly associated with CMV DNAemia. CMV‐specific T cell assays have limited clinical utility among CMV R+ kidney recipients who received valganciclovir prophylaxis. On the other hand, the clinical utility of CMV‐specific T cell assays will need to be assessed in a larger cohort of CMV D+/R? kidney recipients who remain at high‐risk of delayed‐onset CMV disease.     

C1q binding is not an independent risk factor for kidney allograft loss after an acute antibody‐mediated rejection episode: a retrospective cohort study

After kidney transplantation, C4d is an incomplete marker of acute antibody‐mediated rejection (AMR) and C1q‐binding donor‐specific antibodies (DSA) have been associated with allograft survival. However, the impact on allograft survival of C1q+ DSA after clinical AMR has not been studied yet. We analysed retrospectively in clinical AMR C4d staining and C1q‐binding impact on allograft survival. We compared clinical, histological and serological features of C4d− and C4d+ AMR, C1q+ and C1q− DSA AMR and analysed C4d and C1q‐binding impact on allograft survival. Among 500 for‐cause kidney allograft biopsies, 48 fulfilled AMR criteria. C4d+ AMR [N = 18 (37.5%)] have significantly higher number class I DSA (P = 0.02), higher microvascular score (P = 0.02) and more transplant glomerulopathy (P = 0.04). C1q+ AMR [N = 20 (44%)] presented with significantly more class I and class II DSA (P = 0.005 and 0.04) and C4d+ staining (P = 0.01). Graft losses were significantly higher in the C4d+ group (P = 0.04) but similar in C1q groups. C4d+ but not C1q+ binding was an independent risk factor for graft loss [HR = 2.65; (1.11–6.34); P = 0.028]. In our cohort of clinical AMR, C4d+ staining but not C1q+ binding is an independent risk factor for graft loss. Allograft loss and patient survival were similar in C1q+ and C1q− AMR.     

Discovery of non‐HLA antibodies associated with cardiac allograft rejection and development and validation of a non‐HLA antigen multiplex panel: From bench to bedside

We analyzed humoral immune responses to nonhuman leukocyte antigen (HLA) after cardiac transplantation to identify antibodies associated with allograft rejection. Protein microarray identified 366 non‐HLA antibodies (>1.5 fold, P < .5) from a discovery cohort of HLA antibody–negative, endothelial cell crossmatch–positive sera obtained from 12 cardiac allograft recipients at the time of biopsy‐proven rejection. From these, 19 plasma membrane proteins and 10 autoantigens identified from gene ontology analysis were combined with 48 proteins identified through literature search to generate a multiplex bead array. Longitudinal sera from a multicenter cohort of adult cardiac allograft recipients (samples: n = 477 no rejection; n = 69 rejection) identified 18 non‐HLA antibodies associated with rejection (P < .1) including 4 newly identified non‐HLA antigenic targets (DEXI, EMCN, LPHN1, and SSB). CART analysis showed 5/18 non‐HLA antibodies distinguished rejection vs nonrejection. Antibodies to 4/18 non‐HLA antigens synergize with HLA donor‐specific antibodies and significantly increase the odds of rejection (P < .1). The non‐HLA panel was validated using an independent adult cardiac transplant cohort (n = 21 no rejection; n = 42 rejection, >1R) with an area under the curve of 0.87 (P < .05) with 92.86% sensitivity and 66.67% specificity. We conclude that multiplex bead array assessment of non‐HLA antibodies identifies cardiac transplant recipients at risk of rejection.     

High proportion of CD95+ and CD38+ in cultured CD8+ T cells predicts acute rejection and infection,respectively, in kidney recipients

The aim of this study was to find noninvasive T-cell markers able to predict rejection or infection risk after kidney transplantation.We prospectively examined T-lymphocyte subsets after cell culture stimulation (according to CD38, CD69, CD95, CD40L, and CD25 expression) in 79 first graft recipients from four centers, before and after transplantation. Patients were followed up for one year.Patients who rejected within month-1 (n = 10) showed high pre-transplantation and week-1 post-transplantation percentages of CD95⁺, in CD4⁺ and CD8⁺ T-cells (P < 0.001 for all comparisons). These biomarkers conferred independent risk for early rejection (HR:5.05, P = 0.061 and HR:75.31, P = 0.004; respectively). The cut-off values were able to accurately discriminate between rejectors and non-rejectors and Kaplan–Meier curves showed significantly different free-of-rejection time rates (P < 0.005). Patients who rejected after the month-1 (n = 4) had a higher percentage of post-transplantation CD69⁺ in CD8⁺ T-cells than non-rejectors (P = 0.002). Finally, patients with infection (n = 41) previously showed higher percentage of CD38⁺ in CD8⁺ T-cells at all post-transplantation times evaluated, being this increase more marked in viral infections. A cut-off of 59% CD38⁺ in CD8⁺ T-cells at week-1, week-2 and month-2 reached 100% sensitivity for the detection of subsequent viral infections.In conclusion, predictive biomarkers of rejection and infection risk after transplantation were detected that could be useful for the personalized care of kidney recipients.     

Donor‐specific anti‐HLA antibodies detected by Luminex: predictive for short‐term but not long‐term survival after heart transplantation

In heart transplantation, the clinical significance of pretransplant donor‐specific antibodies (DSA) detected by solid phase assay (SPA), which is more sensitive than the conventional complement‐dependent cytotoxicity (CDC) assays, is unclear. The aim was to evaluate SPA performed on pretransplant sera for survival after heart transplantation. Pretransplant sera of 272 heart transplant recipients were screened for anti‐HLA antibodies using CDC and SPA. For determination of pretransplant DSA, a single‐antigen bead assay was performed. The presence of anti‐HLA antibodies was correlated with survival. Secondary outcome parameters were acute cellular rejection, graft coronary vasculopathy and ejection fraction. In Kaplan–Meier analysis, SPA‐screening did not predict survival (P = 0.494), this in contrast to CDC screening (P = 0.002). However, the presence of pretransplant DSA against HLA class I was associated with decreased short‐term survival compared to non‐DSA (P = 0.038). ROC curve analysis showed a sensitivity of 76% and specificity of 73% at a cutoff of 2000 MFI. In contrast, the presence of anti‐HLA antibodies had no influence on long‐term survival, rejection incidence, and graft function. Thus, detection of DSA class I in pretransplant serum is a strong predictor of short‐term, but not long‐term survival and may help in the early management of heart transplant patients.     

Mannose‐Binding Lectin–Deficient Donors Increase the Risk of Bacterial Infection and Bacterial Infection–Related Mortality After Liver Transplantation

Mannose‐binding lectin (MBL) is synthesized by the liver and binds to microbes. MBL2 gene polymorphisms produce intermediate/low/null or normal MBL serum levels (MBL‐deficient or MBL‐sufficient phenotypes, respectively). We aimed to evaluate the incidence and severity of infection, rejection, and survival within 1 year after liver transplantation (LT) according to donor and recipient MBL2 gene polymorphisms. A repeated‐event analysis for infection episodes (negative binomial regression, Andersen–Gill model) was performed in 240 LTs. Four hundred twenty‐eight infectious episodes (310 bacterial, 15 fungal, 65 cytomegalovirus [CMV]‐related, and 38 viral non–CMV‐related episodes) and 48 rejection episodes were recorded. The main bacterial infections were urinary (n = 82, 26%) and pneumonia (n = 69, 22%). LT recipients of MBL‐deficient livers had a higher risk of bacterial infection (incidence rate ratio [IRR] 1.48 [95% confidence interval 1.04–2.09], p = 0.028), pneumonia (IRR 2.4 [95% confidence interval 1.33–4.33], p = 0.013), and septic shock (IRR 5.62 [95% confidence interval 1.92–16.4], p = 0.002) compared with recipients of MBL‐deficient livers. The 1‐year bacterial infection–related mortality was higher in recipients of MBL‐deficient versus MBL‐sufficient livers (65.8% vs. 56.1%, respectively; p = 0.0097). The incidence of rejection, viral, or fungal infection was similar in both groups. Recipient MBL2 genotype did not significantly increase the risk of bacterial infection. LT recipients of MBL‐deficient livers have a higher risk of bacterial infection, pneumonia, septic shock, and 1‐year bacterial infection–related mortality after LT.     

Cytomegalovirus infection and graft rejection as risk factors for pneumocystis pneumonia in solid organ transplant recipients: A systematic review and meta‐analysis

A growing number of publications have reported the outbreaks of post‐transplant pneumocystis pneumonia (PJP). In most studies, the onset of PJP was beyond 6‐12 months of prophylaxis. Cytomegalovirus (CMV) infection and allograft rejection have been repeatedly reported as probable risk factors for post‐transplant PJP. In this systematic review and meta‐analysis, we determined the pooled effect estimates of these 2 variables as risk factors. Data sources included PUBMED, MEDLINE‐OVID, EMBASE‐OVID, Cochrane Library, Networked Digital Library of Theses and Dissertations, World Health Organization, and Web of Science. We excluded publications related to hematopoietic stem cell transplantation (HSCT) or Human Immunodeficiency Virus (HIV) patients. Eventually, 15 studies remained for the final stage of screening. Cytomegalovirus infection (OR: 3.30, CI 95%: 2.07‐5.26, I²: 57%, P = 0.006) and allograft rejection (OR:2.36, CI95%: 1.54‐3.62, I2: 45.5%, P = 0.05) significantly increased the risk of post‐transplant PJP. Extended prophylaxis targeting recipients with allograft rejection or CMV infection may reduce the risk of PJP.     

A quantitative assessment model of T‐cell immune function for predicting risks of infection and rejection during the early stage after liver transplantation

Although more and more clinical studies indicated that ImmuKnow assay could efficiently assess the immune status of recipients, it still has the challenge to predict the occurrence of clinical adverse events. This study aimed to establish a quantitative assessment model, which could more efficiently predict immune function of T lymphocytes after liver transplantation based on three indexes: CD4+ T lymphocyte count (C), CD4+/CD8+ ratio (R), and ImmuKnow adenosine triphosphate (ATP) value (A). We selected 194 recipients and measured the A, C, and R index every week, then obtained the Fisher linear discriminant functions by SPSS 16.0. Next, we divided the recipients into three groups: infection, stable, and rejection groups according to clinical status. After calculating, the discriminant function, 0.012A + 0.019C + 1.322R (simplified into T = 2A + 3C + 200R), was selected to represent the T‐cell‐mediated immune function. Based on the model, the optimal cutoff T values for infection and rejection were 1415 (sensitivity = 80%, specificity = 79.9%,AUC = 92.3%) and 1939.5 (sensitivity = 93.9%, specificity = 77.6%, AUC = 88.6%), relatively (p < 0.001). In conclusion, this model may be a more feasible way to evaluate the cellular immune function status in liver transplantation recipients.     

Noninvasive detection of graft injury after heart transplant using donor‐derived cell‐free DNA: A prospective multicenter study

Standardized donor‐derived cell‐free DNA (dd‐cfDNA) testing has been introduced into clinical use to monitor kidney transplant recipients for rejection. This report describes the performance of this dd‐cfDNA assay to detect allograft rejection in samples from heart transplant (HT) recipients undergoing surveillance monitoring across the United States. Venous blood was longitudinally sampled from 740 HT recipients from 26 centers and in a single‐center cohort of 33 patients at high risk for antibody‐mediated rejection (AMR). Plasma dd‐cfDNA was quantified by using targeted amplification and sequencing of a single nucleotide polymorphism panel. The dd‐cfDNA levels were correlated to paired events of biopsy‐based diagnosis of rejection. The median dd‐cfDNA was 0.07% in reference HT recipients (2164 samples) and 0.17% in samples classified as acute rejection (35 samples; P = .005). At a 0.2% threshold, dd‐cfDNA had a 44% sensitivity to detect rejection and a 97% negative predictive value. In the cohort at risk for AMR (11 samples), dd‐cfDNA levels were elevated 3‐fold in AMR compared with patients without AMR (99 samples, P = .004). The standardized dd‐cfDNA test identified acute rejection in samples from a broad population of HT recipients. The reported test performance characteristics will guide the next stage of clinical utility studies of the dd‐cfDNA assay.