Browsing by Author "Tafulo, S."
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- Clinical implications of anti-HLA antibodies testing in kidney transplantationPublication . Malheiro, J.; Tafulo, S.Alloantibodies against donor human leukocyte antigens (HLA), termed as donor‑specific antibodies (DSA), are one of the most important factors for both early and late kidney allograft dysfunction. In the past, these antibodies were mainly detected through cell‑based crossmatch tests. Recently, new techniques such as solid phase immunoassays (SPI) have revealed these antibodies in patient sera with a high degree of detail, previously unimaginable. They have allowed us to accurately determine recipients’ allosensitization status, improve pre‑transplant risk assessment with a potential donor and post‑transplant alloimmune monitoring. However, the high sensitivity of these new assays has also created areas of uncertainty about their clinical impact. In the pre‑transplant setting, the presence of preformed DSA has been associated with an increased risk of antibody‑mediated rejection (AMR) and subsequent allograft loss. Nevertheless, several studies have shown that not all DSA are deleterious. Hence, understanding the clinical correlations of DSA characteristics, namely strength, HLA class, complement‑fixing ability or IgG subclasses, is paramount for an adequate stratification of the immunological risk at transplant. Furthermore, given that the number of allosensitized patients on waiting lists is increasing, the added information from these new SPI is essential to improve their chance of being transplanted with an admissible immunological risk. After transplantation, the appearance of de novo DSA (dnDSA) has also been associated with a deleterious effect on kidney allograft survival. Moreover, it has been acknowledged that a majority of late allograft failures are caused by alloantibody‑driven injury. The current challenges, in this setting, are determining cost‑effective DSA screening protocols and understanding which patients could benefit from specific interventions. Furthermore, although therapeutic strategies to control antibody‑induced damage remain limited, the longitudinal surveillance of dnDSA emergence and the clinical correlations of their characteristics will play a crucial role in the improvement of late kidney allograft survival.
- Impact of pre-transplant anti-MICA sensitization in graft rejection and survivalPublication . Costa, R.; Malheiro, J.; Tafulo, S.; Santos, C.; Almeida, M.; Pedroso, S.; Martins, L.; Dias, L.; Castro-Henriques, A.Background: Evidence supporting deleterious effect of preformed major histocompatibility class I chain-related A (MICA) antibodies in rejection incidence and graft survival is still unclear. Methods: Retrospective analysis of 554 kidney transplanted patients. Comparison between positive or negative for MICA antibodies patients was performed to characterize sensitizing triggers. Further classification according to pre-transplant flow cytometry-recorded anti–MICA and/or anti-human leukocyte antigen (HLA) antibodies was made to determine first year rejection incidence and graft survival. Multivariate analysis was applied to determine predictors for acute rejection. Results: Pre-formed anti-MICA antibodies were detected in 41 patients (7.4%). HLA sensitization, blood transfusions and pregnancies were frequently found in anti-MICA+ patients but only pre-formed anti-HLA class I antibodies showed independent association (OR 2.67, p= 0.02). Comparing to MICA-/HLA–, MICA-/HLA+ group presented significantly lower first year rejection-free survival (78.6% vs. 89.3%, p< 0.01), mostly occurred in the first six months, while no difference was found in MICA+/HLA– (88.9% vs. 89.3%, p= ns). MICA-/HLA+ showed independent impact in rejection (OR 2.09, p= 0.03), while no evidence was found in MICA+/HLA- (OR 1.08, p= ns). At 4 years, MICA-/HLA+ group presented lower graft survival (85.8% vs. 95.3%, p= 0.03). Again, no difference was found in MICA+/HLA- group (95.1% vs. 95.3%, p= ns). Conclusion: Our results do not support HLA-independent deleterious pathogenic role of pre-formed MICA antibodies on first year rejection incidence and graft survival.
- Impact of preformed donor-specific antibodies against HLA class I on kidney graft outcomes: Comparative analysis of exclusively anti-Cw vs anti-A and/or -B antibodiesPublication . Santos, S.; Malheiro, J.; Tafulo, S.; Dias, L.; Carmo, R.; Sampaio, S.; Costa, M.; Campos, A.; Pedroso, S.; Almeida, M.; Martins, L.; Henriques, C.; Cabrita, A.AIM: To analyze the clinical impact of preformed antiHLA-Cw vs antiHLA-A and/or -B donor-specific antibodies (DSA) in kidney transplantation. METHODS: Retrospective study, comparing 12 patients transplanted with DSA exclusively antiHLA-Cw with 23 patients with preformed DSA antiHLA-A and/or B. RESULTS: One year after transplantation there were no differences in terms of acute rejection between the two groups (3 and 6 cases, respectively in the DSA-Cw and the DSA-A-B groups; P = 1). At one year, eGFR was not significantly different between groups (median 59 mL/min in DSA-Cw group, compared to median 51 mL/min in DSA-A-B group, P = 0.192). Moreover, kidney graft survival was similar between groups at 5-years (100% in DSA-Cw group vs 91% in DSA-A-B group, P = 0.528). The sole independent predictor of antibody mediated rejection (AMR) incidence was DSA strength (HR = 1.07 per 1000 increase in MFI, P = 0.034). AMR was associated with shortened graft survival at 5-years, with 75% and 100% grafts surviving in patients with or without AMR, respectively (Log-rank P = 0.005). CONCLUSION: Our data indicate that DSA-Cw are associated with an identical risk of AMR and impact on graft function in comparison with "classical" class I DSA.
- Implications for patients waiting for a kidney transplant of using the calculated panel reactive antibody (cPRA)Publication . Magriço, R.; Malheiro, J.; Tafulo, S.; Pedroso, S.; Almeida, M.; Martins, L.; Dias, L.; Castro-Henriques, A.; Cabrita, A.Introduction: Kidney transplant improves survival even in highly‑sensitized (HS) patients. To overcome their disadvantage in accessing transplantation, those with high Complement Dependent Cytotoxic PRA (CDC‑PRA) receive additional points during allocation. Whether this strategy reaches all HS patients and how long they wait for a transplant is largely undetermined. Methods: Patients on our unit’s active wait‑list for kidney transplantation in the year 2014 were analyzed. CDC‑PRA and calculated PRA (cPRA) were recorded. To obtain cPRA, antibodies in the last serum available specific for HLA‑A, ‑B or –DR with an intensity > 1000 MFI were considered. Results: The cPRA values in the population (N=551) were 0% (N=312), 1‑79% (N=118) and ≥ 80% (22%; N=121). Among these groups, the proportion of women (29.5, 55.9 and 61.2%, P<0.001), prior sensitizing events (43.3, 80.5 and 96.7%, P<0.001) and time on dialysis (median of 3.9, 4.1 and 6.0 years, P<0.001) increased with cPRA, respectively. In most of those with a cPRA ≥ 80%, the CDC‑PRA raised no suspicion of HS status (median 0%, P25‑75 0‑8%) and only 35 (28.9%) or 12 patients (9.9%) had a CDC‑PRA in the peak serum higher than 50 or 80%, respectively (cut‑offs needed to obtain additional points during allocation). HS patients by cPRA corresponded to 71% vs 15% of patients waiting for ≥ or <8 years, respectively (P<0.001). Even after exclusion of patients with a CDC‑PRA above 50%, this disproportionate representation remained (58% versus 13%, P<0.001). Conclusion: HS patients as measured by cPRA remained longer on the wait‑list, both in the primary analysis and when excluding those with a CDC‑PRA> 50%. Moreover, only 30% of HS by cPRA patients received the extra points designed to improve their transplantability. We consider that both CDC‑PRA and cPRA should be taken into account when defining HS status.
- Posttransplant allosensitization in low immunological risk kidney and kidney-pancreas graft recipients.Publication . Malheiro, J.; Tafulo, S.; Dias, L.; Martins, La Salete; Fonseca, Isabel; Almeida, M.; Pedroso, S.; Freitas, F.; Beirão, I.; Castro-Henriques, A.; Cabrita, A.INTRODUCTION: Posttransplantation allosensitization prevalence and effect on kidney grafts outcomes remain unsettled. METHODS: Between 2007 and 2012, 408 patients received a primary kidney graft (with 68 patients also receiving a pancreas graft) after a negative cytotoxic crossmatch. All patients had a pretransplant negative anti-HLA screening and 0% panel reactive antibodies. We analyzed retrospectively the results of anti-HLA antibodies screening by Luminex assay, performed between 6 and 24 months after transplant, and searched for the risk factors for antibody positivity and its impact on kidney graft outcomes. RESULTS: Anti-HLA antibodies prevalence at 6 months was 17.4%. Previous steroid-insensitive acute rejection was the only risk factor for both anti-HLA classes detected antibodies. Antithymocyte globulin induction was also a risk factor for anti-HLA-I antibodies. Antibody positivity status was associated with reduced graft function at 12 months and graft survival at 5 years (91.5% versus 96.4%, P = 0.03). In multivariable Cox analysis, delayed graft function (HR = 6.1, P < 0.01), HLA mismatches >3 (HR = 10.2, P = 0.03), and antibody positivity for anti-HLA class II (HR = 5.1, P = 0.04) or class I/II (HR = 13.8, P < 0.01) were independent predictors of graft loss. CONCLUSIONS: Allosensitization against HLA class II ± I after transplant was associated with adverse kidney graft outcomes. A screening protocol seems advisable within the first year in low immunological risk patients.