Chiara Sabia

Comprehensive assessment of sensitizing events and anti-HLA antibody development in women awaiting kidney transplantation

BACKGROUND Alloimmunization remains a critical factor which affects the success of kidney transplantation. Patients awaiting solid organ transplantation may develop anti-HLA antibodies after pregnancies, transfusions and previous events of transplantations. AIM We evaluated the effects of different sensitizing events on the anti-HLA antibody production and the potential role of patient HLA alleles in the context of antibody development in both the overall and pregnancy sensitized groups. MATERIAL AND METHODS We retrospectively stratified 411 women on waiting list for kidney transplantation by route of sensitization. The presence of anti-HLA antibodies was evaluated by Solid Phase Assay and HLA typing was performed by serological and molecular methods. RESULTS In our study population, 54% of women had anti-HLA antibodies. We found that the 51.6% of women with pregnancy only, 44% of women with transfusion only and 100% of women with a history of transplantation only developed anti-HLA antibodies. Pregnancy only resulted significantly associated with all anti-HLA antibody development such as anti-A, -B, -C, -DR, -DP as well as anti-DQB and -DQA antibodies. We investigated the influence of patient HLA alleles on the antibody development in the overall study population. Patients expressing HLA A*32 (p=0.024, OR=0.42), B*14 (p=0.035, OR=0.44), HLA-B*44 (p=0.026, OR=0.51) and DRB1*01 (p=0.029, OR=0.55) alleles produced anti-HLA antibodies less frequently compared to subjects with other alleles. In the pregnancy only group, B*14 (p=0.010, OR=0.12) and B*51 (p=0.005, OR=0.24) alleles were associated with a low risk of anti-HLA antibody development, while A*11 (p=0.033, OR=3.56) and DRB1*04 (p=0.022, OR=3.03) alleles seem to represent a higher risk. CONCLUSIONS Pregnancy still remains a strong sensitizing event in women awaiting kidney transplantation. The anti-HLA antibody development in pregnancy appears to be associated with the expression of particular HLA alleles.

Screening tests for hepatitis B virus, hepatitis C virus, and human immunodeficiency virus in blood donors: Evaluation of two chemiluminescent immunoassay systems

Abstract Automated chemiluminescent immunoassays (CLIAs) are useful for the detection of hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus 1/2 antigen/antibodies (HIV 1/2 Ag/Ab) in blood donor screening. Eight hundred and forty serum samples were tested for hepatitis B surface antigen (HBsAg), HCV antibodies (anti-HCV), and HIV1/2 Ag/Ab in parallel using 2 different CLIAs (Abbott Architect i2000SR and Roche Cobas e411). The concordance between the 2 systems was high (Cohens kappa 0.97 for HBsAg, 0.77 for anti-HCV, 0.92 for HIV1/2 Ag/Ab) and the specificity and the positive predictive value were comparable. Among the 12 discrepant results, 11 were false-positive and 1 (reactive by Architect) was true-positive for anti-HCV. Positivity for HBV DNA, HCV RNA, and HIV RNA was recorded in 90.9%, 38.9%, and 100% of true-positive samples, respectively. This study represents the first stringent comparison between Architect i2000SR and Cobas e411 in blood donors. We observed a good correlation and high agreement among HBV, HCV, and HIV with the 2 automated systems.

Syphilis detection: evaluation of serological screening and pilot reverse confirmatory assay algorithm in blood donors.

Serological assays are still considered the most useful tests in the diagnosis of syphilis. Since no single serological assay is able to provide a satisfactory result, in our laboratory we have evaluated the usefulness of a commercially-available immunoblot to diagnose syphilis infection among blood donors. From October 2012 to June 2013, 4572 blood donors were screened for syphilis with an automated chemiluminescent microparticle immunoassay (CMIA). To confirm the presence of treponemal antibodies, CMIA-reactive sera were tested by standard Treponema pallidum haemagglutination assay (TPHA). In addition, an alternative confirmatory test – the immunoblot INNO-LIA assay was introduced in our laboratory. Since two additional positives among CMIA-reactive-TPHA-negative samples were found, we concluded that the INNO-LIA immunoblot allowed a better detection of syphilis compared to TPHA. A confirmatory strategy based on the use of two treponemal assays could meet the screening requirements for blood donors as well as in our centre.

Comparison of performance of two Treponema pallidum automated chemiluminescent immunoassays in blood donors

Abstract The recrudescence of syphilis is leading to the development of new serological tests. The goal of this study was to compare the performance of the more recent Elecsys Syphilis assay, the Electro Chemiluminescence Immunoassay (ECLIA), with the former Architect Syphilis TP assay, the Chemiluminescent Microparticle Immunoassay (CMIA), for the detection of antibodies against Treponema pallidum in blood donors. Serum samples of 5543 voluntary blood donors were screened in parallel with two tests. All repeatedly reactive (RR) samples by one or both assays were further analysed for confirmation by immmunoblot INNO-LIA and TPHA. Of 32 RR samples by CMIA, 21 were confirmed positive; of 21 RR samples by ECLIA, 20 were confirmed positive. The sensitivities of CMIA and ECLIA were 100% and 95.24% (95% CI = 85.71–100), respectively, not significant (p > 0.05). The specificity and predictive positive value (PPV) of CMIA were 99.86% (95% CI = 99.74–99.94) and 72.41%, respectively, while the specificity and PPV of ECLIA were both 100%, being statistically significant (p = 0.01 for both). The overall agreement was 99.80% and the Cohen’s kappa coefficients was 0.79. In conclusion, the recent Elecsys Syphilis assay could represent another reliable assay for blood donor screening.

Heart transplant with donor-specific antibody after immunoadsorption plus rituximab: a case report

Different desensitization strategies are available for treating patients with preformed human leukocyte antigen (HLA) antibodies. A highly presensitized heart recipient received immunoadsorption and rituximab therapy. The patient, with end-stage heart failure, was positive only for antibodies of HLA class I (anti-A2, A10, B17), and Luminex platform (One Lambda kit) showed a panel-reactive antibody score of 64%. The patients serum was tested repeatedly in both complement-dependent cytotoxicity and flow-cytometry crossmatches against cells from different potential organ donors. The results of these crossmatches were positive on flow cytometry when tested with HLA-A2, A10, and B17 but were still negative on cytotoxicity. The patient was treated with a desensitization regimen; this treatment immediately decreased antibody levels of 70% and the patient subsequently received a transplant with donor-specific HLA antibody (HLA-A2). After more than 2 years, graft function remains normal and the clinical status of the patient is stable.

Association between human leukocyte antigen class I and II alleles and hepatitis C virus infection in high-risk hemodialysis patients awaiting kidney transplantation

Recent evidences have shown that several host genetic factors influence susceptibility or protection to hepatitis C virus (HCV) infection. There are controversial data regarding the associations of human leukocyte antigens (HLA) and the clearance or progression of HCV. The aim of this study was to investigate whether particular HLA molecules were associated with HCV infection in recipients awaiting kidney transplantation considered at high-risk to infection due to protracted hemodialysis treatment. To this purpose, 301 kidney recipients with HCV infection and 1103 uninfected recipients were examined for HLA class I and II molecules. In our case-control study, HLA-A(*)26 is positively associated with HCV infection while HLA-A(*)29, -B(*)40 and -DRB1(*)01 are negatively associated with HCV infection. Multiple logistic regression analysis demonstrated that age (OR = 1.02; 95% CI = 1.01-1.04; p < 0.00), HLA-A(*)26, -A(*)29, -B(*)40 and -DRB1(*)01 [(OR = 1.54; 95% CI = 1.03-2.30; p = 0.03); (OR = 0.50; 95% CI = 0.26-0.99; p = 0.05); (OR = 0.42; 95% CI = 0.23-0, 7; p = 0.01); (OR = 0.62; 95% CI = 0.41-0, 94; p = 0.03); respectively] are independent predictors of HCV infection. Our results suggest that particular HLA molecules, as host genetic factors, may have a relationship with susceptibility or protection to HCV infection also in recipients awaiting kidney transplantation.

Transplantation and host immune response to Toxoplasma gondii

C. Sabia, M.L. Montesano, C. Napoli. Transplantation and host immune response to Toxoplasma gondii. Transpl Infect Dis 2013: 15: E124–E125. All rights reserved C. Sabia, M.L. Montesano, C. Napoli U.O.C. Division of Immunohematology, Transfusion Medicine and Transplantation Immunology (SIMT) and Regional Reference Laboratory of Immunogenetics and Transplantation Immunology (LIT), Second University of Naples, Italy, Department of General Pathology, Chair of Clinical Pathology and Excellence Research Centre on Cardiovascular Diseases, Second University of Naples, Italy

HLA-G and anti-HCV in patients on the waiting list for kidney transplantation

PURPOSE Human leukocyte antigen (HLA)-G is a non-classic major histocompatibility complex HLA class I molecule. HLA-G may have tolerogenic properties which are linked to epigenetic-sensitive pathways. There is a correlation of sHLA-G levels and graft acceptance in transplantation studies. There are previous data on correlation of sHLA-G with graft rejection as well as with viral infections such as hepatitis C virus (HCV) in kidney transplanted patients. Here, we report the sHLA-G expression in patients on the waiting list for kidney transplantation, with and without anti-HCV compared to a control group. METHODS Serum of 67 patients on the waiting list for kidney transplantation (n = 43 with anti-HCV and n = 24 without anti-HCV) was analyzed. Among these patients, n = 39 were on the waiting list for the first transplantation, while n = 28 were patients who returned in the list. The control group included n = 23 blood donors with anti-HCV (n = 13) and without anti-HCV (n = 10). RESULTS The expression of sHLA-G was significantly lower in the control group (39.6 ± 34.1 U/ml) compared to both - patients on the waiting list for the first transplantation (62.5 ± 42.4 U/ml, p=0.031) and patients who returned in the list (76.7 ± 53.9 U/ml, p=0.006). No significant differences were observed in all anti-HCV positive groups. A positive linear correlation between sHLA-G and TNF-α, and patient age was observed. CONCLUSIONS Serum sHLA-G values were significantly increased in both - patients on the waiting list for the first transplantation and patients who returned in the list, as compared to control group. Our findings confirm the key tolerogenic role of sHLA-G levels as epigenetic-related marker for measuring the state of kidney allograft acceptance.

The epigenetic promise to improve prognosis of heart failure and heart transplantation

Heart transplantation is still the only possible life-saving treatment for end-stage heart failure, the critical epilogue of several cardiac diseases. Epigenetic mechanisms are being intensively investigated because they could contribute to establishing innovative diagnostic and predictive biomarkers, as well as ground-breaking therapies both for heart failure and heart transplantation rejection. DNA methylation and histone modifications can modulate the innate and adaptive immune response by acting on the expression of immune-related genes that, in turn, are crucial determinants of transplantation outcome. Epigenetic drugs acting on methylation and histone-modification pathways may modulate Treg activity by acting as immunosuppressive agents. Moreover, the identification of non-invasive and reliable epigenetic biomarkers for the prediction of allograft rejection and for monitoring immunosuppressive therapies represents an attractive perspective in the management of transplanted patients. MiRNAs seem to fit particularly well to this purpose because they are differently expressed in patients at high and low risk of rejection and are detectable in biological fluids besides biopsies. Although increasing evidence supports the involvement of epigenetic tags in heart failure and transplantation, further short and long-term clinical studies are needed to translate the possible available findings into clinical setting.