Efficacy of plasmapheresis and semi-selective immunoadsorption for removal of anti-HLA antibodies.

BACKGROUND: In organ transplantation, apheresis is frequently used for removal of anti-HLA antibodies. However, it is unclear whether plasmapheresis (PP) or semi-selective immunoadsorption (IA) should be employed, and the optimal number of apheresis sessions required to reach post-treatment objectives is also unknown. METHODS: We enrolled 43 patients from Bordeaux University Hospital who were treated with PP (n = 29) or IA (n = 14) for antibody-mediated rejection or pre-transplant desensitization. Using Luminex single-antigen flow beads, we assessed the initial mean fluorescence intensity (MFI) of 1416 positive beads with MFIs obtained after 7 to 8 apheresis sessions (extended protocol) and, if a serum was available, after the first four sessions (short protocol). RESULTS: MFI reduction after extended apheresis protocol was stronger with IA [87% (61%-100%)] than with PP [73% (22%-100%)] (P < .001). Indeed, 59% of the beads had a final MFI < 2000 with IA, whereas only 38% with PP (P < .001). The efficacy of removal depended on initial MFI but not on HLA specificity. A short protocol of apheresis showed excellent results without superiority of IA over PP for antibodies with an initial MFI < 3000. For antibodies showing MFI ≥2000 after four sessions, the residual MFI predicted the effectiveness of four additional sessions. CONCLUSION: Monitoring the MFI of anti-HLA antibodies before and during apheresis protocol can guide physicians in the selection of apheresis technique and the number of sessions to be performed.

Frequência de anticorpos irregulares identificados em pacientes atendidos em um hemonúcleo no sudoeste do Paraná no ano de 2017 / Frequency of irregular antibodies identified in patients treated at the hemotherapy service in southwest of Paraná in 2017

Quando um indivíduo é exposto a antígenos eritrocitários não próprios, ocorre uma resposta imunológica, que leva à produção de anticorpos irregulares voltados contra esses antígenos. Esse processo é conhecido como aloimunização eritrocitária e acontece em decorrência de transfusões de sangue ou gestações incompatíveis. Na medicina transfusional a pesquisa de anticorpos irregulares é fundamental, pois a falha na detecção de um aloanticorpo pode provocar reações transfusionais, aloimunizações, anemias hemolíticas autoimunes e doença hemolítica perinatal. Este estudo tem por objetivo analisar a frequência de anticorpos irregulares de pacientes atendidos no Hemocentro Regional de Francisco Beltrão, Paraná, no ano de 2017. Os dados foram coletados a partir da revisão de registros em arquivos do Laboratório de Imunohematologia do Hemonúcleo. Foram avaliados dados de 49 protocolos de pacientes que apresentaram dificuldades transfusionais no ano de 2017. Dentre os pesquisados, 37 pacientes (75,5%) apresentaram anticorpos irregulares. Dentre os anticorpos anti-eritrocitários observados neste estudo, evidenciou-se a presença de doze pacientes com anti-D (27,2%), seis pacientes com anti-K (13,6%), quatro pacientes com anti-C (9,0%) e em seis pacientes (13,6%) foi observada a presença de autoanticorpos. Este estudo indica que, nos pacientes transfundidos, os anticorpos mais frequentes foram os aloanticorpos Anti-D do Sistema Rh, provavelmente devido ao seu alto grau de imunogenicidade. A prevalência desses anticorpos é semelhante a vários estudos encontrados na literatura.

When an individual is exposed to not-self red blood cell antigens, an immune response occurs, which leads to the production of irregular antibodies directed against these antigens. This process is known as erythrocyte alloimmunization and occurs as a result of blood transfusions or incompatible pregnancies. In transfusion medicine, the search for irregular antibodies is essential, since failure to detect an alloantibody can cause transfusion reactions, alloimmunizations, autoimmune hemolytic anemias, and perinatal hemolytic disease. This study aims at analyzing the frequency of irregular antibodies of patients seen at the Regional Blood Center of Francisco Beltrão, Paraná, in 2017. The data were collected from the review of records in files of the Immunohematology Laboratory of Hemonúcleo. Data from 49 protocols of patients who had transfusion difficulties in 2017 were evaluated. Among those surveyed, 37 patients (75.5%) had irregular antibodies. Among the anti-erythrocyte antibodies observed in this study, the presence of twelve patients with anti-D (27.2%), six patients with anti-K (13.6%), four patients with anti-C (9.0 %), and in six patients (13.6%) with the presence of autoantibodies were observed. This study indicates that, in transfused patients, the most frequent antibodies were the Rh System Anti-D alloantibodies, probably due to their high degree of immunogenicity. The prevalence of these antibodies is similar to several studies found in the literature.

Red Blood Cell Alloantibody Titration - Does the Titration Method Matter?

BACKGROUND: Red blood cell (RBC) alloantibody titration is a quasi-quantitative method to assess antibody concentration and is considered a useful means of estimating maternal alloimmunization during pregnancy. Traditionally, titration is performed using conventional tube test (CTT). The gel microcolumn agglutination-based method (GMA) has been proven reliable for many immunohematology tests. Our study compared CTT with GMA of two different, commercially available GMA systems for RBC alloantibody titration. METHODS: Serum samples with significant RBC-alloantibodies were evaluated in our study. Each sample was titrated concurrently with CTT, with ID-DiaMed-GmbH, Cressier, Switzerland (GMA1), and with DG Gel Coombs Diagnostic Grifols, Passeig Fluvial, Spain (GMA2). RESULTS: One hundred thirty-seven titration tests including 50 anti-D, 25 anti-Kell, 10 anti-E, 9 anti-Jka, 8 anti-c, 5 anti-Cw, 5 anti-Fya, 7 anti-M, 6 anti-Kpa, 3 anti-Lua, 1 anti-e, 3 anti-G, and 2 anti-Cha were performed and evaluated. Samples tested by CTT versus GMA1 and GMA2 generated mostly equal or higher titers by GMAs. The results of both comparisons were in good agreement (W = 0.91, p < 0.0001, and W = 0.92, p < 0.0001, respectively). For all antibody specificities, the mean absolute difference in titers ranged from 1 - 3 for both GMA1 and GMA2 versus CTT. Samples tested by GMA1 vs. GMA2 were in almost perfect agreement (W = 0.95, p < 0.0001). CONCLUSIONS: Although both GMAs were found slightly more sensitive than CTT for alloantibody titration, the differences were not significant and the agreement between all methods was very good, possibly indicating GMA as a suitable alternative to CTT in RBC antibody titration.

Development of Functional Antibodies Directed to Human Dialyzable Leukocyte Extract (Transferon®).

Transferon® is an immunomodulator made of a complex mixture of peptides from human dialyzable leucocyte extracts (hDLEs). Development of surrogate antibodies directed to hDLE is an indispensable tool for studies during process control and preclinical trials. These antibodies are fundamental for different analytical approaches, such as identity test and drug quantitation, as well as to characterize its pharmacokinetic and mechanisms of action. A previous murine study showed the inability of the peptides of Transferon® to induce antibody production by themselves; therefore, in this work, two approaches were tested to increase its immunogenicity: chemical conjugation of the peptides of Transferon® to carrier proteins and the use of a rabbit model. Bioconjugates were generated with Keyhole Limpet Hemocyanin (KLH) or Bovine Serum Albumin (BSA) through maleimide-activated carrier proteins. BALB/c mice and New Zealand rabbits were immunized with Transferon® conjugated to KLH or nonconjugated Transferon®. Animals that were immunized with conjugated Transferon® showed significant production of antibodies as evinced by the recognition of Transferon®-BSA conjugate in ELISA assays. Moreover, rabbits showed higher antibody titers when compared with mice. Neither mouse nor rabbits developed antibodies when immunized with nonconjugated Transferon®. Interestingly, rabbit antibodies were able to partially block IL-2 production in Jurkat cells after costimulation with Transferon®. In conclusion, it is feasible to elicit specific and functional antibodies anti-hDLE with different potential uses during the life cycle of the product.

Manejo de la anemia perioperatoria en paciente con aloanticuerpos programada para esofagectomía / Management of peri-operative anaemia in a patient with rare alloantibodies scheduled for oesophagectomy

Describimos el manejo de una paciente programada para esofagectomía por neoplasia a la que durante el proceso de reserva de hemoderivados le fueron detectados aloanticuerpos, que prácticamente imposibilitaban la obtención de sangre compatible. El manejo de la anemia perioperatoria («patient blood management») se debe realizar rutinariamente en los pacientes quirúrgicos con riesgo de transfusión. Esta estrategia se ha considerado como una de las medidas a tener en cuenta en la rehabilitación multimodal quirúrgica o programa de recuperación intensificada

A description is presented on the management of a patient with an oesophageal neoplasm scheduled for oesophagectomy. Alloantibodies were detected during a blood components reservation procedure, which made it almost impossible to obtain compatible blood. Peri-operative anaemia management or "Patient Blood Management" should be routinely performed in all patients at transfusion risk. This strategy has been considered as one of the actions to bear in mind in fast-track surgery or enhanced recovery after surgery

Class II Human Leukocyte Antigen Epitope Mismatch Predicts De Novo Donor-Specific Antibody Formation After Liver Transplantation.

Formation of de novo donor-specific antibodies (dn-DSAs) has been associated with longterm immunologic complications after liver transplantation (LT). We hypothesized that human leukocyte antigen (HLA) epitope/eplet mismatch (MM) is a marker of immunogenicity and a risk factor for dn-DSA formation. Sera from 80 LT recipients were prospectively screened for dn-DSA by a Luminex single-antigen test (One Lambda, Inc., Canoga Park, CA) at 1, 2, 3, 6, 12, 18, 24, and 36 months after LT. HLA typing of the recipients and donors was performed using polymerase chain reaction (PCR)-SSP and PCR-SSOP Luminex low-resolution methods (One Lambda, Inc.). The HLAMatchmaker computer algorithm was used for identification of MM eplets at HLA-DRB1 and -DQA1/B1 loci. Luminex single-antigen bead solid phase assay was used for antibody analysis. Standard immunosuppression included thymoglobulin-rituximab induction and tacrolimus maintenance. There were 27 (34%) patients who developed dn-DSA. There were no episodes of antibody-mediated rejection, and 9 (11%) developed acute cellular rejection (ACR). A positive crossmatch status and a higher number of HLA-A, -B, -DR, and -ABDR MMs were not associated with dn-DSA formation. Patients developing dn-DSA had a significantly higher number of total (38 ± 2.7 versus 28 ± 2.3; P = 0.01) and antibody-verified (AbVer; 14 ± 1.1 versus 10 ± 1; P = 0.015) class II MM eplets. By a multivariate regression analysis, the number of class II MM eplets was strongly associated with risk of class II dn-DSA formation (odds ratio [OR], 1.2; P < 0.01). Patients with ACR had a significantly higher number of total (20.2 ± 1.3 versus 13.9 ± 0.9; P < 0.01) as well as AbVer (10.7 ± 1.1 versus 7.5 ± 0.6; P = 0.03) class I MM eplets. In conclusion, donor-recipient HLA epitope MM is associated with a risk of dn-DSA formation and rejection after LT. However, further studies are required to evaluate the clinical utility of epitope matching in LT.

Prevalence, Risk Factors, and Impact of Donor-Specific Alloantibodies After Adult Liver Transplantation.

The incidence and impact of anti-human leukocyte antigen donor-specific alloantibodies (DSAs) developing after liver transplantation (LT) remains controversial and not extensively studied. The aim of the present study was to assess the incidence of DSAs, to identify risk factors for the development of DSAs, and to understand the impact of DSAs in a large population of adult LT recipients. This single-center retrospective study included all adult patients who underwent a first LT between 2000 and 2010 in our center. The study population mainly consisted of male patients, the mean age was 52.4 years, and the main indication was alcoholic cirrhosis (54.1%). From the 297 patients included in the cross-sectional study, 14 (4.7%) had preformed DSAs, and 59 (19.9%) presented de novo DSAs (12.2% at 1 year, 13.4% at 5 years, and 19.5% at 10 years). Multivariate analysis found that female donor sex (hazard ratio [HR], 1.50; 95% confidence interval [CI], 1.12-2.01; P = 0.01) and delay between LT and DSA screening (HR, 1.10; 95% CI, 1.01-1.20; P = 0.03) were associated with occurrence of de novo DSAs. From the 190 patients included in the subgroup longitudinal analysis, exposure to tacrolimus (mean trough level during the periods 0-2 years and 0-3 years) was significantly lower for patients having DSAs at 5 years. Concerning histology, only acute rejection (P = 0.04) and portal fibrosis ≥2 (P = 0.02) were more frequent at 1 year for patients with DSAs. Patient survival and graft survival were not significantly different according to the presence or not of DSAs at 1 year. Among the 44 patients who had de novo or persistent preformed DSAs, the diagnosis of antibody-mediated rejection was made in 4 (9.1%) patients after 1, 47, 61, and 74 months following LT. In conclusion, the results of the present study suggest that DSAs are observed in a minority of LT adult patients, with limited overall impact on graft and patient outcome.

Ficin-Treated Red Cells Help Identify Clinically Significant Alloantibodies Masked as Reactions of Undetermined Specificity in Gel Microtubes.

Non-specific antibodies or antibodies of undetermined significance (AUS) often pose problems for a blood bank technologist and physician. It is well known that antibodies can weaken and evanesce over time, thus eluding detection by routine blood bank techniques. Special enhancement techniques exist (eg, ficin treatment); however, they are often underutilized due to concerns over expense. Ficin is known to enhance reactivity caused by antibodies in the ABO, Rh, Kidd, Lewis, I, and P blood group systems, while destroying reactivity of antibodies in the Duffy, and MNS blood group systems. Herein, we discuss our protocol for using ficin treatment to determine the specificity of antibodies that would otherwise be classified as AUS. Of the 97 AUS specimens that were treated with ficin, we were able to identify 25 new alloantibodies that would have otherwise been missed without ficin treatment. Thus, we believe our protocol enhances transfusion safety, while minimizing additional workload and cost.

Prophylactic anti-D preparations display variable decreases in Fc-fucosylation of anti-D.

BACKGROUND: RhIG is obtained from hyperimmunized healthy anti-D donors (HIDs) boosted with D+ red blood cells (RBCs). One hypothesis for its mechanism of action is fast clearance of opsonized D+ RBCs through Fcγ receptor (FcγR)III. Levels of immunoglobulin (Ig)G Fc-fucosylation influence interactions with FcγRIII, with less Fc-fucosylation strengthening the interaction. STUDY DESIGN AND METHODS: Anti-D IgG1 Fc-glycosylation patterns in 93 plasma samples from 28 male and 28 female Dutch HIDs and RhIG were analyzed with mass spectrometry. The Fc-glycosylation profiles of HIDs were evaluated with regard to their immunization history. RESULTS: HID sera demonstrated clearly lowered anti-D Fc-fucosylation compared to normal IgG fucosylation (93%); this was more pronounced for female than for male HIDs (47% vs. 65%, p = 0.001). RhIG preparations from seven manufacturers varied greatly in the level of Fc-fucosylation (56%-91%). The level of fucosylation slightly increased upon repeated immunization, although it remained fairly constant over time. The RhIG from the different manufacturers all demonstrated increased Fc-galactosylation (64%-82%) compared to total IgG (38%-51%). CONCLUSION: RhIG preparations vary in Fc-fucosylation and all demonstrate increased galactosylation. Despite not knowing the exact working mechanism, immunoprophylaxis could perhaps be optimized by selection of donors whose anti-D have low amounts of Fc-fucose, to increase the clearance activity of anti-D preparations, as well as high amounts of galactosylation, for anti-inflammatory effects. Implementing a biologic assay in the standardization of RhIG preparations might be considered.

Antibody screening & identification in the general patient population at a tertiary care hospital in New Delhi, India.

BACKGROUND & OBJECTIVES: The development of alloantibodies can significantly complicate transfusion therapy and results in difficulties in cross-matching of blood. Most literature on alloimmunization is limited to multitransfused individuals, with very few studies on the general hospital patients. This study was aimed at assessing the frequency and type of unexpected red cell antibodies in the general patient population at a multispecialty tertiary care centre in New Delhi, India. METHODS: The results of 49,077 antibody screening tests carried out on patients, from January 2009 to December 2012 were analyzed. The clinical and transfusion records were reviewed. The data were compiled and statistically analysed. RESULTS: A total of 49,077 (29,917; 60.96% males and 19,160; 39.04% females) patient samples were screened for the presence of unexpected antibodies. Antibody screening was positive in 403 patients (0.82%). In the serum samples of 164 patients only autoantibodies were identified, 27 revealed autoantibodies with one or more underlying alloantibodies, while 212 patients had only alloantibody/ies in their serum. The overall alloimmunization rate was 0.49 per cent. Antibodies against the Rh system were the most frequent (64.1%), the most common alloantibody identified being anti E (37.2%), followed by anti D (19.2%). INTERPRETATION & CONCLUSIONS: Since clinically significant antibodies are frequently detected in our patient population, antibody screening and if required, identification is the need of the hour. Since antibodies against the common Rh and Kell blood group antigens are the most frequent, provision of Rh and Kell matched red cells may be of protective value.