Effects of Rituximab on Atherosclerotic Biomarkers in Kidney Transplant Recipients.

INTRODUCTION: Cardiovascular disease is the leading cause of mortality in kidney transplant recipients. Rituximab is widely used in kidney transplantation for a variety of situations, and rituximab may inhibit some cytokines and antibodies that may play an active role in the atherosclerotic process. The aim of the study was to evaluate the efficacy of rituximab on atherosclerosis biomarkers in kidney transplant recipients. METHODS: All patients, 18 years of age and older, who underwent kidney transplantation and received at least 1 dose of 375 mg/m2 rituximab were considered for participation in this study. The primary study endpoint was the development of cardiovascular diseases after rituximab therapy. The secondary endpoint was the onset of cytomegalovirus (CMV) disease or biopsy-confirmed BK virus nephropathy. In addition, comparison of atherosclerosis biomarkers was performed between study and control groups. RESULTS: There were no cardiovascular events observed during follow up. Only 8 patients in the study group suffered from CMV disease during follow up. Serum interleukin 10 levels were significantly higher in the rituximab group compared with the control group, although anti-oxidized low-density lipoprotein levels were lower in the rituximab group compared with the control group, though this did not achieve statistical significance. DISCUSSION: Rituximab treatment may increase the risk of CMV reactivation and decrease lymphocyte counts and interleukin 10 levels; however, significant decreases in all atherosclerotic-related biomarkers have not been shown in our study.

Panel Reactive Antibody Responses Against Influenza Vaccination in Kidney Transplant Recipients.

INTRODUCTION: Seasonal influenza is an important cause of morbidity and mortality in the post-transplant period; therefore, the influenza vaccination has been recommended for all kidney transplant recipients before the influenza season. However, at least theoretically, the introduction of antigens via vaccines may trigger rejection attacks by causing an antibody response. In this study, we examined the development of de novo panel reactive antibody (PRA) development against the influenza vaccine in kidney transplant recipients. MATERIALS AND METHODS: Overall, 41 kidney transplant recipients who received the influenza vaccination and 50 kidney transplant recipients (study group) who refused to receive the influenza vaccination (control group) were enrolled in the study. Following basal biochemistry examination, the inactivated trivalent influenza vaccine was administered intramuscularly. Panel reactive antibodies were screened in all patients before and after vaccination on days 30 and 180. The primary outcome variable was development of de novo panel reactive antibodies. RESULTS: One patient in the study group developed de novo class I and II PRA at 6 months after vaccination (P > .05), while no antibody development was noted in the control group. Graft dysfunction or biopsy-confirmed rejection was not observed during the follow-up period in both groups. CONCLUSION: The influenza vaccination is generally effective and safe in solid organ transplant recipients. The vaccination procedure has the potential to trigger antibody development and occurrence of rejection. Therefore, vaccinated kidney transplant recipients should be monitored more carefully with regard to PRA; if the graft deteriorates, a rapid transplant biopsy should be performed.

Association Between HLA Antibodies and Different Sensitization Events in Renal Transplant Candidates.

BACKGROUND: Human leukocyte antigen (HLA) allo-immunization is caused by various events such as blood transfusions, pregnancies, or organ transplantations, which can lead to sensitization. In this retrospective study, we evaluated different sensitization models and their effects on panel-reactive antibody (PRA) profiles of renal transplantation candidates. METHODS: Anti-HLA class I/II antibody screening tests were performed in 906 renal transplantation candidates with the use of a microbead-based assay (Luminex). RESULTS: Two hundred ninety-seven (32.8%) of the patients were determined as positive in terms of PRA, and 609 (67.2%) were negative. Sensitized and non-sensitized patients were compared separately in terms of each sensitization type. The anti-HLA class I, II, and I+II positivity rates in patients sensitized only by blood transfusion were 13.1%, 6.3%, and 14.1%, the rates with pregnancy sensitization were 35.5%, 29%, and 45.2%, and rates with previous transplantation sensitization were 15.6%, 34.4%, and 38.9%, respectively. Prevalence of PRA positivity was significantly higher in patients with previous pregnancy than with transplantation and transfusion (odds ratio, 1.003; 95% confidence interval, 0.441-2.281; P = .031). The risk of developing HLA class I antibodies was higher in pregnancies (P < .001), and the risk of developing anti-HLA class II antibodies was higher in patients who had undergone a previous transplantation (P < .001). The rate of developing HLA-B antibodies in patients sensitized by pregnancy were significantly higher compared with sensitization after transfusion (P = .015), as was the rate of developing HLA-DQ antibodies in patients sensitized by previous transplantation compared with sensitization through pregnancy (P = .042). CONCLUSIONS: In patients who are waiting for kidney transplantation, sensitization by pregnancy and transplantation have a significant impact on development of HLA class I and class II antibodies.

Corrected Panel-Reactive Antibody Positivity Rates for Hypersensitized Patients in Turkish Population With Calculated Panel-Reactive Antibody Software.

INTRODUCTION: High rates of panel-reactive antibody (PRA) may decrease the chance of kidney transplantation and may result in long waiting periods before transplantation. The calculated PRA (cPRA) is performed based on unacceptable HLA antigens. These antigens are identified by a program that was created based on the antibodies that developed against the HLA antigens circulating in serum and on the risk of binding of these antibodies to antigens. The antigen profile of the population and antigen frequencies can be measured, and more realistic cPRA positivity rates may be obtained using this method. MATERIALS AND METHODS: We developed a program based on the HLA antigens of 494 blood donors in 2 European Federation for Immunogenetics-accredited Tissue Typing Laboratories in Turkey. Next-generation sequencing-based tissue typing (HLA-A, -B, -C, -DR, -DQ, 4 digits) of the samples was performed. The PRA screening test was performed on 380 patients who were waiting for organ transplant from a cadaver in Istanbul Faculty of Medicine. The single antigen bead assay testing was performed to identify the antibody profiles on 48 hypersensitized patients. RESULTS: The PRA testing results using the current methods were 44.6% ± 18.5%, and the cPRA rate was 86.2% ± 5.1%. The mean PRA positivity of the sensitized patients using the current methods was 44.6%; however, the rate was 86.2% using the cPRA. DISCUSSION: cPRA shows the rate of the rejected donors according to all unacceptable antigens. The need for a list of unacceptable antigens in place of the PRA positivity rate is a real change in the sensitization-dependent calculation as cPRA positivity rate. CONCLUSION: In principal, implementation of cPRA will encourage many centers and laboratories to adopt a standard measurement of sensitization in Turkey. It will increase the chances of better donor match, particularly for hypersensitized patients, by the creation of an unacceptable mismatch program using cPRA software.

Tac-MMF Versus CsA-MMF/CsA-AZA-Based Regimens in Development of De Novo Complement-Binding Anti-HLA Antibodies After Kidney Transplantation.

BACKGROUND: Immunosuppressive regimens with tacrolimus or cyclosporine A (CsA) were compared for graft-related outcomes in conjunction with complement-binding de novo donor-specific antibodies (DSAs). METHODS: Non-sensitized adult patients without rejection episodes within 3 months after transplantation were screened for the presence of de novo DSAs and C1q binding. Clinical and biopsy data were retrospectively obtained. RESULTS: The analysis included 118 patients (68 tacrolimus, 50 CsA), with mean age and follow-up of 36.1 ± 11.4 and 7.2 ± 4.8 years, respectively. As compared with tacrolimus, the CsA group had higher rates of both class II DSAs and C1q-binding DSAs (20% vs 4.4%, P = .008, and 18% vs 0%, P = .003, respectively). Rates of chronic antibody-mediated rejection (cAMR), proteinuria >500 mg/g, and levels of creatinine both at last visits were also higher in the CsA group (20% vs 0%, P = .002, 30% vs 5.9%, P = .005, 1.67 ± 1.31 vs 1.18 ± 0.45 mg/dL, P = .019, respectively).Class II DSAs and C1q-binding class II DSAs were significantly correlated with the clinical outcomes (creatinine levels, proteinuria, and cAMR). CONCLUSIONS: Compared with tacrolimus, CsA appears to pose a higher risk for the development of de novo anti-HLA antibodies with C1q-binding properties and, consequently, adverse graft-related outcomes.

Relevance of Flow Cytometric Auto-Crossmatch to the Post-transplant Course of Kidney Transplant Recipients.

INTRODUCTION: The crossmatch test is essential prior to kidney transplantation (tx) to confirm compatibility between the donor and the recipient. However, its results can be misleading due to "undetectable antibodies" in the recipient's serum. To establish if undetectable autoantibodies are responsible for a positive result, an auto-crossmatch test can be performed. In this study, we aim to determine the long-term prognostic value of auto-flow cytometric auto-crossmatch (FCXM) test on kidney survival in kidney tx recipients. MATERIALS AND METHODS: The primary outcome variable was reduced renal function. Secondary endpoints were incidence of biopsy-confirmed chronic antibody-mediated rejection (CAMR) and recurrent glomerulonephritis (GN). RESULTS: There were no differences regarding initial serum creatinine levels between the study and control groups (P = .441). Patients who had positive auto-B FCXM had a significantly reduced renal function compared with the control group (P = .016). Four patients developed biopsy-confirmed CAMR in the study group and 1 patient in the control group (P = .047). Five patients had biopsy-confirmed recurrent GN in the GN study group, and only 1 patient had recurrent GN in the GN control group (P = .026). DISCUSSION: Kidney transplant recipients with positive auto-FCXM test had significantly reduced renal function and a higher incidence of recurrent GN and CAMR compared with the control group. The findings of this study suggest a potential role of auto-antibody causing positive auto-FCXM test result, meanwhile increasing the risk of CAMR, recurrent GN, and new-onset diabetes after tx.

A Novel Biomarker for Post-Transplant Recurrent IgA Nephropathy.

BACKGROUND: The serum levels of galactose-deficient immunoglobulin (Ig)A1 (Gd-IgA1) represent the most promising candidate biomarker for IgA nephropathy (IgAN). The aim of this study was to evaluate the serum levels of Gd-IgA1 as a novel noninvasive biomarker for post-transplant IgAN recurrence. METHODS: Serum Gd-IgA1 levels of 18 patients with recurrent IgAN were compared with control renal transplant recipients (n = 23) with non-recurrent IgAN and control non-transplant IgAN patients (n = 44) and healthy relatives (n = 11). Serum Gd-IgA1 levels of patients were measured with the use of KM55 enzyme-linked immunosorbent assay (ELISA). The effects of serum Gd-IgA1 concentrations on IgAN recurrence, post-transplant events, and graft survival were evaluated. RESULTS: All recurrent IgAN patients presented with renal dysfunction (mean serum creatinine, 1.62 ± 0.39 mg/dL) and detectable proteinuria at the time of diagnosis. Serum Gd-IgA1 levels of recurrent IgAN patients (8735 ± 10854 ng/mL [log10: 3.71 ± 0.45]) were significantly higher than those of non-recurrent IgAN patients (4790 ± 6089 ng/µL [log10: 3.31 ± 0.64]) (P = .027). Serum Gd-IgA1 levels of non-transplant IgAN patients were significantly higher (8791 ± 8700 ng/µL [log10: 3.79 ± 0.36]) than those of non-recurrent IgAN patients (4790 ± 6089 ng/µL [log10: 3.31 ± 0.64]) and healthy relatives (2615 ± 1611 ng/µL [log10: 3.34 ± 0.27]) (P < .001 and P = .021, respectively). Receiver-operating characteristic curve analysis revealed that the area under the curve for recurrence of IgAN was 0.69 (0.53-0.85) for serum Gd-IgA1 (P = .038). Biopsy-confirmed allograft rejection rates were similar in the recurrent IgAN group [3 (17%)] compared with the non-recurrent IgAN [6 (26%)] group (P = .47). Graft failure rate was not also significantly different in the recurrent IgAN group [4 (22.2%)] compared with the non-recurrent IgAN group [2 (8.7%)] (P = .224). CONCLUSIONS: This novel lectin-independent Gd-IgA1 ELISA that can detect serum Gd-IgA1 in patients with recurrent IgAN can be used as a biomarker for diagnosis and activity assessment of post-transplant recurrent IgAN.

The effect of anti-human leukocyte antigen, anti-major histocompatibility complex class 1 chain-related antigen a, and anti-glutathione transferase-T1 antibodies on the long-term survival of renal allograft.

BACKGROUND: One of the most important mechanisms of allograft rejection is the production of donor-specific antibodies (DSA). Anti-major histocompatibility complex class-I chain-related antigen A (MICA) and anti-glutathione S transferase-T1 (GSTT1) antibodies cause graft dysfunction and reduce graft survival. The aim of this study was to examine the effects of anti-human leukocyte antigen class I-II, anti-MICA, and anti-GSTT1 antibodies in development of antibody-mediated rejection. METHODS: Among the 32 renal transplant patients included in this study 65% experienced antibody-mediated rejection (AMR; chronic active AMR [CAMR], n = 17; acute AMR [AAMR], n = 4) and 35%, ACR. The anti-HLA class I-II and anti-MICA antibodies were determined by using LUMINEX, anti-GSTT1 antibodies by enzyme-linked immunosorbent assay. GSTT1 genotyping of patients and donors was performed by polymerase chain reaction. RESULTS: Antibody was detected in 19 of 21 patients undergoing antibody-mediated rejection (90%). We detected anti-GSTT1 in 4, anti-MICA in 8, anti-HLA class I in 5, and anti-HLA class II in 9 patients with CAMR (P = .007). If the patients were divided into 2 groups according to being C4d(+) and C4d(-) both anti-HLA class I and class II antibodies were found significantly more frequently among the C4d(+) group (P = .019, P = .024). No difference was determined between AMR and ACR groups in terms of anti-GSTT1 and anti-MICA antibodies. CONCLUSIONS: In this study, we observed the role of anti-HLA class II antibodies in the development of CAMR and in long-term allograft survival. It is observed that anti-MICA and anti-GSTT1 antibodies showed no effect on rejection mechanisms.

The effect of glutathion S-transferase polymoprhisms and anti-GSTT1 antibodies on allograft functions in recipients of renal transplant.

The balance between oxidative stress and anti-oxidant defense systems after renal transplantation may explain the development and progression of allograft dysfunction. Glutathione S-transferase (GST) decreases the damage from oxidative stress. In contrast, recipient antibodies against GSTT1 expressed on the graft are believed to cause its dysfunction. The aim of our research was to study the probable relationship to rejection between GST gene polymorphisms and anti-GSTT1 antibodies. We included 122 patients transplantations from living donors and 51 healthy individuals as controls group in our study. The patient groups were comprised of 57 patients who did and 65 who did not experienced rejection episode. Polymerase chain reactions were used to detect GSTM1 and GSTT1 polymorphisms, whereas PCR-RFLP (restriction fragment length polymorphism), for GSTP1 polymorphism. An enzyme-linked immunosorbent assay method was used for anti-GSTT1 antibody scans. There was no significant difference between the groups for allele and genotype frequencies of GSTT1, GSTM1, GSTP1 polymorphisms of the recipients, donors, and controls. Within the rejection group the frequency of patients with the GSTM1 null genotype was higher among subjects prescribed cyclosporine A versus tacrolimus (P = .029). Among the entire patient group, 46 subjects with GSTT1 null genotype were scanned for anti-GSTT1 antibody which was detected in 5 of 8 patients with an acute rejection episode (P = .04). Anti-GSTT1 antibody was observed more frequently albeit not significantly, among the cyclosporine versus tacrolimus patient group (P = .16). This study suggested that GSTM1 genotype may be important for cyclosporine detoxification and for allograft outcomes due to drug nephrotoxicity. After transplantation, antigens distinct from the HLA system such as GSTT1 protein may also be targets for alloimmune responses.