Dangerous universal donors: the reality of the Hemocentro in Belo Horizonte, Minas Gerais

Background: The term dangerous universal blood donor refers to potential agglutination of the erythrocytes of non-O recipients due to plasma of an O blood group donor, which contains high titers of anti-A and/or anti-B hemagglutinins. Thus, prior titration of anti-A and anti-B hemagglutinins is recommended to prevent transfusion reactions. Objective: The aim ofthis study was to estimate the frequency of dangerous universal donors in the blood bank of Belo Horizonte (Fundac¸ão Central de Imuno-Hematologia ­ Fundac¸ão Hemominas ­ Minas Gerais) by determining the titers of anti-A and anti-B hemagglutinins in O blood group donors. Method: A total of 400 O blood group donors were randomly selected, from March 2014 to January 2015. The titers of anti-A and anti-B hemagglutinins (IgM and IgG classes) were obtained using the tube titration technique. Dangerous donors were those whose titers of anti-A or anti-B IgM were ≥128 and/or the titers of anti-A or anti-B IgG were ≥256. Donors were characterized according to gender, age and ethnicity. The hemagglutinins were characterized by specificity (anti-A and anti-B) and antibody class (IgG and IgM). Results: Almost one-third (30.5%) of the O blood group donors were universal dangerous. The frequency among women was higher than that of men (p-value = 0.019; odds ratio: 1.66; 95% confidence interval: 1.08­2.56) and among young donors (18­29 years old) it was higher than for donors between 49 and 59 years old (p-value = 0.015; odds ratio: 3.05; 95% confi- dence interval: 1.22­7.69). There was no significant association between dangerous universal donors and ethnicity, agglutinin specificity or antibody class. Conclusion: Especially platelet concentrates obtained by apheresis (that contain a substantial volume of plasma), coming from dangerous universal donors should be transfused in isogroup recipients whenever possible in order to prevent the occurrence of transfusion reactions

Impact of a confirmatory RhD test on the correct serologic typing of blood donors

BACKGROUND: The RHD gene is highly polymorphic, which results in a large number of RhD variant phenotypes. Discrepancies in RhD typing are still a problem in blood banks and increase the risk of alloimmunization. In this study, the RhD typing strategy at a blood bank in Brazil was evaluated.METHODS: One-hundred and fifty-two samples typed as RhD negative and C or E positive by routine tests (automated system and indirect antiglobulin test using the tube technique) were reevaluated for RhD status by three methods. The method with the best performance was implemented and evaluated for a period of one year (n = 4897 samples). Samples that were D positive exclusively in the confirmatory test were submitted to molecular analysis.RESULTS: The gel test for indirect antiglobulin testing with anti-D immunoglobulin G (clone ESD1) presented the best results. Seventy samples (1.43%) previously typed as RhD negative showed reactivity in the gel test for indirect antiglobulin testing and were reclassified as D positive. D variants that may cause alloimmunization, such as weak D type 2 and partial DVI, were detected.CONCLUSION: The confirmatory RhD test using the gel test for indirect antiglobulin testing represents a breakthrough in transfusion safety in this blood center. Our results emphasize the importance of assessing the blood group typing strategy in blood banks.

Alloimmunization screening after transfusion of red blood cells in a prospective study

BACKGROUND: Several irregular red blood cell alloantibodies, produced by alloimmunization of antigens in transfusions or pregnancies, have clinical importance because they cause hemolysis in the fetus and newborn and in transfused patients. OBJECTIVE: a prospective analysis of patients treated by the surgical and clinical emergency services of Hospital de Clínicas of the Universidade Federal do Triângulo Mineiro (HC/UFTM), Brazil was performed to correlate alloimmunization to clinical and epidemiological data. METHODS: Blood samples of 143 patients with initial negative antibody screening were collected at intervals for up to 15 months after the transfusion of packed red blood cells. Samples were submitted to irregular antibody testing and, when positive, to the identification and serial titration of alloantibodies. The Fisher Exact test and Odds Ratio were employed to compare proportions. RESULTS: Fifteen (10.49%) patients produced antibodies within six months of transfusion. However, for 60% of these individuals, the titers decreased and disappeared by 15 months after transfusion. Anti-K antibodies and alloantibodies against antigens of the Rh system were the most common; the highest titer was 1:32 (anti-K). There was an evident correlation with the number of transfusions. CONCLUSIONS: Given the high incidence of clinically important red blood cell alloantibodies in patients transfused in surgical and clinical emergency services, we suggest that phenotyping and pre-transfusion compatibilization for C, c, E, e (Rh system) and K (Kell system) antigens should be extended to all patients with programmed surgeries or acute clinical events that do not need emergency transfusions.

Molecular analysis of the GYPB gene to infer S, s, and U phenotypes in an admixed population of Minas Gerais, Brazil

OBJECTIVE: To implement genotyping for S, s and U antigens of the MNS blood group system at the Fundação Hemominas and to evaluate the occurrence of GYPB gene polymorphisms associated with the U- and U+var phenotypes and deletion of the GYPB gene for the first time in an admixed population of Minas Gerais, Brazil. The S, s and U antigens can cause transfusion reactions and perinatal hemolytic disease. Genotyping is a useful tool in immunohematology, especially when phenotyping cannot be performed. METHODS: Ninety-six samples from blood donors and patients with sickle cell disease previously phenotyped for the S, s and U antigens were selected. Allele-specific primer polymerase chain reaction (ASP-PCR) and polymerase chain reaction -restriction fragment length polymorphism (PCR-RFLP) assays were employed to identify the GYPB*S and GYPB*s alleles and the GYPB(P2) and GYPB(NY) variants, as well as deletion of the GYPB gene. RESULTS: The results of allele-specific genotyping (GYPB*S and GYPB*s) were totally in agreement with the phenotyping of S+ (n = 56), s+ (n = 60) and s- (n = 35) samples. However, the GYPB*S allele, in association with the GYPB(P2) variant, was detected in 17.5% of the S- samples (n = 40), which shows the importance of assessing this variant in the Brazilian population. Of the S-s- samples (n = 10), 60% had the deletion of the GYPB gene and 40% were homozygous or hemizygous for the GYPB(P2) variant. CONCLUSION: Genotyping was an effective strategy to infer the S, s, and U phenotypes in the admixed population from Minas Gerais (Brazil) and may contribute to transfusion safety.

Genotipagem RhD fetal não invasiva no acompanhamento de gestantes RhD negativo / Non invasive Fetal RHD Genotyping in management of pregnant RhD negative women

O acompanhamento de gestantes de fenótipo RhD negativo é baseado na premissa de que seus fetos podem estar em risco de desenvolver a doença hemolítica perinatal (DHPN) ou eritroblastose fetal, trazendo sérios riscos ao feto em decorrência de hemólise, com consequente anemia, hidropsia e, por vezes, óbito intrauterino. Procedimentos invasivos como amniocentese ou cordocentese podem ser utilizados para se inferir o fenótipo RhD fetal, entretanto, oferecem riscos ao feto e à gestante. Nos últimos anos, o conhecimento sobre a genética dos grupos sanguíneos e o desenvolvimento de técnicas de biologia molecular tem permitido a inferência de fenótipos de grupos sanguíneos a partir da detecção do material genômico. Inicialmente, a genotipagem do DNA fetal para o gene RhD era feita a partir de amostras de amniócitos ou de vilosidades coriônicas. No entanto, por tratar-se de testes invasivos, traziam risco ao feto e à gestante. A possibilidade de se obter DNA fetal a partir do plasma materno foi um grande avanço na prática clínica, por ser um procedimento não invasivo e, portanto, isento de risco. Esta revisão apresenta os princípios da técnica e os resultados de diferentes protocolos para genotipagem RhD fetal (publicados ao longo dos anos) e qual o seu propósito no acompanhamento das gestantes RhD negativo

The RhD negative pregnant women management has been based on the fact that their fetuses may be at risk of developing hemolytic diseases (DHPN) or erythroblastosis fetalis. This condition may bring serious risks to the fetus due to hemolysis, with consequent anemia and hydrops and sometimes, intrauterine death. Invasive procedures such as amniocentesis or cordocentesis may be performed to assess the fetal RhD phenotype, however, it offers risks to both fetus and pregnant woman. In recent years, the knowledge about the genetics of blood groups and the development of molecular biology techniques has allowed the inference of blood group phenotypes by the detection of genomic material. Initially, the fetal DNA genotyping for the RHD gene was performed from amniocytes or chorionic villi samples. Unfortunately, these invasive tests could bring risk to the fetus and the pregnant woman. However, the possibility of obtaining fetal DNA from maternal plasma has been a major advance in clinical practice, as being a non-invasive procedure and therefore not providing any risks. This review presents the principles of techniques and results of different protocols for fetal RHD genotyping (published over the years) and its goal on the management of RhD negative pregnant women

Existem evidências que justifiquem o congelamento do próprio cordão umbilical? / Is there evidence that justifies freezing our own umbilical cord?

O transplante de células progenitoras hematopoéticas é um procedimento eficaz para o tratamento de doenças hematológicas malignas ou não malignas, distúrbios imunológicos e metabólicos. Entre as fontes conhecidas de células progenitoras hematopoéticas, o sangue de cordão umbilical e placentário tem se destacado, cada vez mais, como fonte segura. É amplamente empregado na realização de transplantes em pacientes que não possuem doadores HLA compatíveis entre os familiares ou em registros de doadores de medula. O sangue de cordão pode ser utilizado em transplantes alogênicos, autólogos ou alogênicos apresentados. Existe uma grande controvérsia quanto à utilidade e à probabilidade da utilização autóloga de sangue de cordão umbilical e placentário. Nesta revisão, discutimos os principais aspectos do processo de armazenamento e a relevância clínica do sangue de cordão umbilical, assim como as questões controversas em relação ao seu emprego autólogo.

Hematopoietic progenitor cell transplantation is an effective procedure for the treatment of malignant or non-malignant hematologic diseases, immune and metabolic disorders. Among the known sources of hematopoietic progenitor cells, cord blood has increasingly emerged as a reliable one, and is widely used to perform transplantations in patients who have no HLA compatible donors among relatives or bone marrow donor's registries. Cord blood can be used in allogeneic, autologous or related allogeneic transplantations. There is great controversy regarding the usefulness and therapeutic effect of using autologous cord blood. In this review we discuss the main aspects of collection, cryopreservation and clinical utility of umbilical cord blood, as well as issues regarding its autologous use.

Atualizações na profilaxia da isoimunização Rh / Updates in the prophylaxis of the Rh isoimmunization

O conhecimento da isoimunização Rh e das bases moleculares do gene RHD e de suas variantes cresceu muito nos últimos anos. Esse crescimento permitiu a introdução de ferramentas realmente úteis no acompanhamento a gestantes isoimunizadas ou em risco de desenvolver a doença hemolítica perinatal (DHPN). A introdução da imunoprofilaxia RhD, por volta dos anos 1960, propiciou uma significativa redução na incidência de aloimunização materna por anti-D. Essa redução torna-se ainda mais significante quando há a associação da profilaxia pós-natal à antenatal, entretanto, seu uso ainda não é amplamente difundido no Brasil e sua eficiência está diretamente relacionada à dose correta, que vai depender da idade gestacional e da quantidade de hemorragia feto-materna (HFM). Sabe-se ainda que a imunoglobulina anti-D policlonal, por ser de origem humana, não é isenta de riscos à gestante ou ao concepto. Dada essa limitação, anticorpos monoclonais têm sido produzidos e avaliados a fim de substituir o anti-D policlonal. Todavia, até o momento, o sucesso dessa nova tecnologia tem sido apenas parcial. Como uma importante alternativa, entretanto, tem sido estudada a habilidade de indução de tolerância à proteína RhD, em ratos transgênicos, a partir de peptídios sintéticos

The knowledge of the Rh isoimmunization and the molecular bases of RHD gene and its variants has grown in recent years. This growth allowed the introduction of useful tools in monitoring pregnant women with alloimmunization or at risk of developing hemolytic disease of the newborn (HDN). The introduction of RhD immunoprophylaxis, in the 1960 years, provided a significant reduction in the incidence of maternal alloimmunization by anti-D. This reduction becomes even more significant when associated with antenatal prophylaxis, however, its use is not yet widespread in Brazil and its efficiency is directly related to the correct dose that will depends on the gestational age and the fetomaternal hemorrhage (FMH) quantity. It is also known that anti-D polyclonal, to be of human origin, is not without risk to the mother or the fetus. Given this limitation, monoclonal antibodies have been produced and evaluated in order to replace the polyclonal anti-D. Nevertheless, so far the success of this new technology has been only partial. As an important alternative, however, the ability to induce tolerance to the RhD protein in transgenic mice from synthetic peptides has been studied