The relevance of a bank with genotyped platelets donors

ABSTRACT Objective: Describe the clinical and laboratory characteristics and the transfusion strategy of patients at Hospital Israelita Albert Einstein with platelet refractoriness and identify their etiological characteristics. Standardize the platelet immunofluorescence technique by flow cytometry as a test for platelet compatibility in immune platelet refractoriness in transfusion support. Methods: Review of medical records of refractory platelet patients followed at HIAE from January 2011 to May 2017. Clinical-demographic data, laboratory data and identification of the use of compatible genotyped platelets for patients in need of transfusion therapy were collected. The analyzed patients were classified according to the etiology of their platelet refractoriness. To standardize the FC-PIFT technique, blood group O platelets were incubated with serum from blood group AB donors and anti-IgG monoclonal antibody to determine the negative control. In order to verify the influence of the ABO system, monoclonal anti-IgG antibodies were incubated with blood group A or B platelets and with blood group O donor serum with isohemagglutinins below and above 1/64. Results: A total of 47 patients were evaluated, a 51% (24/47) preponderance of associated immune and non-immune factors (NIPR + IPR). The most common causes of NIPR + IPR were splenomegaly (54%) and the development of HLA antibodies (88%), consistent with the literature. For patients who required therapeutic transfusion, only a small portion received compatible genotyped platelets. Conclusion: Although 60% of patients could benefit from the therapeutic transfusion of genotyped platelets, only 10% were actually transfused with this type of blood component. This reaffirms the need for investments in a bank of genotyped platelet donors.

The relevance of a bank with genotyped platelets donors.

OBJECTIVE: Describe the clinical and laboratory characteristics and the transfusion strategy of patients at Hospital Israelita Albert Einstein with platelet refractoriness and identify their etiological characteristics. Standardize the platelet immunofluorescence technique by flow cytometry as a test for platelet compatibility in immune platelet refractoriness in transfusion support. METHODS: Review of medical records of refractory platelet patients followed at HIAE from January 2011 to May 2017. Clinical-demographic data, laboratory data and identification of the use of compatible genotyped platelets for patients in need of transfusion therapy were collected. The analyzed patients were classified according to the etiology of their platelet refractoriness. To standardize the FC-PIFT technique, blood group O platelets were incubated with serum from blood group AB donors and anti-IgG monoclonal antibody to determine the negative control. In order to verify the influence of the ABO system, monoclonal anti-IgG antibodies were incubated with blood group A or B platelets and with blood group O donor serum with isohemagglutinins below and above 1/64. RESULTS: A total of 47 patients were evaluated, a 51% (24/47) preponderance of associated immune and non-immune factors (NIPR + IPR). The most common causes of NIPR + IPR were splenomegaly (54%) and the development of HLA antibodies (88%), consistent with the literature. For patients who required therapeutic transfusion, only a small portion received compatible genotyped platelets. CONCLUSION: Although 60% of patients could benefit from the therapeutic transfusion of genotyped platelets, only 10% were actually transfused with this type of blood component. This reaffirms the need for investments in a bank of genotyped platelet donors.

Fetal and neonatal alloimmune thrombocytopenia: a late or missed diagnosis disease in fetal and perinatal health-care settings.

INTRODUCTION: Even though Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) has been recognized as the main cause of primary hemorrhagic morbidity and mortality in fetuses and newborns, screening programs to detect pregnancies at risk have not yet been implemented in any country. Moreover, in spite of increased concerns about maternal, fetal and neonatal health care in general, this potentially lethal disease is still underdiagnosed. The aim of this report is to highlight the importance of considering FNAIT in fetal and perinatal health-care settings and show the usefulness of molecular tools in early diagnosis of this clinical entity. METHODS: DNA was extracted from whole blood from parents and newborns; genotyping was performed by in house PCR using sequence-specific primers for typing Human Platelet Antigens (HPA)-1 to -6, -9, and -15, and with commercial HPA-TYPE (BAG HealthCare, Lich, Germany). Anti-HPA antibodies in the maternal serum were detected by the Monoclonal Antibody Solid Phase Platelet antibody Test (MASPAT). Chloroquine-treated platelets were used for the discrimination of platelet-specific antibodies from anti-HLA antibodies. RESULTS: Patients 1 and 2 had severe thrombocytopenia due to incompatibility in HPA-1 and HPA-15, respectively. The third case was a thrombocytopenic neonate with severe bleeding complications other than ICH and in whom differential diagnosis between FNAIT and Von Willebrand congenital disease was necessary; incompatibility in HPA-15 was also demonstrated. Case 4 represents a missed diagnostic opportunity. CONCLUSION: This is the first report of FNAIT cases confirmed by molecular evidence and anti-HPA antibodies detection in Argentina. This report reinforces the relevance of early diagnosis of this clinical entity. Since the delay in FNAIT diagnosis could lead to severe consequences in the fetus and neonates, strategies to approach maternal, fetal, and perinatal health, as well as prevention policies aimed to reduce fetal and neonatal morbidity and mortality should focus on implementing programs to identify high-risk pregnancies and thus reduce thrombocytopenia-related complications in fetuses and newborns.

Human platelet antigen polymorphisms and the risk of chronic Chagas disease cardiomyopathy.

Human platelet antigen (HPA) polymorphisms are considered to be a risk factor for cardiac and vascular diseases, but the role of HPA in chronic Chagas disease cardiomyopathy (CCC) is not available. Therefore, the aim of this study was to investigate the association of HPA polymorphisms, HPA-1, HPA-2, HPA-3, HPA-5 and HPA-15, in the severity of left ventricular systolic dysfunction (LVSD) in CCC patients. For this, 229 CCC patients were separated into three groups: without LVSD, mild/moderate LVSD and severe LVSD. PCR-SSP was performed for HPA genotyping and the risk was assessed using SNPStats software. HPA-1 allele and genotype frequencies were lower in mild/moderate LVSD patients compared to other groups, without statistical significance. After stratified analyzes, the HPA-3a/3b genotype frequency was lower in women with severe LVSD compared to those without LVSD (OR:0.29; 95% CI: 0.10-0.84). In conclusion, HPA-3 variant could be a protection factor for CCC in the female patients.

Human platelet antigen-3 polymorphism as a risk factor for rheumatological manifestations in hepatitis C

Abstract INTRODUCTION: Hepatitis C virus (HCV) infection is involved in the pathogenesis of autoimmune and rheumatic disorders. Although the human platelet antigens (HPA) polymorphism are associated with HCV persistence, they have not been investigated in rheumatological manifestations (RM). This study focused on verifying associations between allele and genotype HPA and RM in patients with chronic hepatitis C. METHODS: Patients (159) with chronic hepatitis C of both genders were analyzed. RESULTS: Women showed association between HPA-3 polymorphisms and RM. CONCLUSIONS: An unprecedented strong association between rheumatological manifestations and HPA-3 polymorphism, possibly predisposing women to complications during the disease course, was observed.

Conocimientos actuales sobre la patogénesis, presentación clínica, diagnóstico y manejo de la trombocitopenia neonatal aloinmune / Current knowledge on neonatal alloimmune thrombocytopenia's pathogenesis, clinical presentation, diagnostic and management

Introducción: La trombocitopenia neonatal aloinmune es una enfermedad producida por anticuerpos maternos contra antígenos plaquetarios fetales heredados del padre. Puede ser causa de hemorragia intracraneal y conducir a la muerte o discapacidad en el feto/neonato. Aunque es la causa más grave de trombocitopenia en el neonato y la más común en los recién nacidos a término, en general ha sido poco investigada. Objetivos: Exponer los conocimientos actuales sobre la patogénesis, presentación clínica, diagnóstico y del manejo pre- y posnatal de la trombocitopenia neonatal aloinmune, Métodos: Se realizó una revisión de la literatura, en inglés y español, a través del sitio web PubMed y el motor de búsqueda Google académico de artículos publicados en los últimos 10 años. Se hizo un análisis y resumen de la bibliografía revisada. Resultados: Los anticuerpos IgG maternos son transportados a través de la placenta a la circulación fetal, opsonizan las plaquetas fetales que son removidas por fagocitosis. Los antígenos más implicados son el HPA-1a y HPA-4a. La fisiopatología de la enfermedad es muy similar a la enfermedad hemolítica perinatal, pero aún no se han implementado programas de pesquisa y el diagnóstico se realiza después del nacimiento del niño afectado de trombocitopenia, hemorragia intracraneal o muerte in útero de causa no explicada. Consideraciones finales: El impacto clínico de la trombocitopenia neonatal aloinmune y las oportunidades de tratamiento potencian la necesidad de implantar programas de pesquisa para la detección de fetos en riesgo de padecer esta enfermedad(AU)

Introduction: Neonatal alloimmune thrombocytopenia is a disease produced by maternal antibodies against fetal platelet antigens inherited from the father. It can be a cause of intracranial hemorrhage and lead to death or disability in the fetus / neonate. Although it is the most serious cause of thrombocytopenia in newborns and the most common in full-term infants, it has generally been poorly investigated. Objectives: To approximate to current knowledge about the pathogenesis, clinical presentation, diagnosis and pre- and post-natal management of neonatal alloimmune thrombocytopenia. Methods: A review of literature, in English and Spanish, through PubMed website and Google scholar search engine of articles published in the last 10 years was conducted. An analysis and summary of the reviewed bibliography was made. Results: Maternal IgG antibodies are transported through the placenta to the fetal circulation, opsonizing fetal platelets that are removed by phagocytosis. The most involved antigens are HPA-1a and HPA-4a. The pathophysiology of this disease is very similar to perinatal hemolytic disease, but research programs have not been implemented yet and diagnosis is made after birth of children affected by thrombocytopenia, intracranial hemorrhage or in uterus death by unexplained causes. Final considerations: Clinical impacts of neonatal alloimmune thrombocytopenia and treatment opportunities enhance the need to implement screening programs for the detection of fetuses at risk of suffering from this disease(AU)

Anticuerpos antiplaquetarios en pacientes cubanos en espera de trasplante renal / Platelet antibodies in cuban patients waiting for renal transplantation

Introducción: Los antígenos específicos de plaquetas, conocidos como antígenos de plaquetas humanas (HPA, del inglés human platelet antigens), se incluyen dentro del espectro de antígenos de histocompatibilidad no-HLA, debido a que los anticuerpos anti-HPA participan en el rechazo del trasplante, además de ser causa del fenómeno de refractariedad plaquetaria. Objetivo: Caracterizar los anticuerpos contra antígenos específicos de plaquetas en pacientes cubanos en espera de trasplante renal. Métodos: Se investigaron muestras de sangre de 901 pacientes mediante la técnica de inmovilización de antígenos plaquetarios con anticuerpos monoclonales. Resultados: En 78 pacientes se detectaron anticuerpos anti-HPA, que en el 87,17 por ciento reconocían los antígenos presentes en el complejo GP-IIb/IIIa. Estos anticuerpos fueron del tipo IgG en el 78,2 por ciento, IgA en el 11,53 por ciento e IgM en el 46,15 por ciento. Conclusiones: En pacientes cubanos en espera de trasplante renal son frecuentes los Ac anti-HPA, en su mayoría del tipo IgG dirigidos contra antígenos presentes en el complejo GP-IIb/IIIa(AU)

Introduction: Platelet-specific antigens, known as human platelet antigens (HPA), are included within the spectrum of non-HLA histocompatibility antigens, because HPA antibodies participate in the rejection of transplantation, besides being a cause of the phenomenon of platelet refractoriness. Objective: To characterize antibodies against platelet-specific antigens in Cuban patients awaiting kidney transplantation. Methods: The technique monoclonal antibodies immobilized platelets antigens was applied to blood samples from 901 patients. Results: HPA antibodies were detected in 78 patients, which in 87.17 percent recognized the antigens present in the GP-IIb / IIIa complex. These antibodies were in 78.2 percent of the IgG class, in 11.53 percent IgA and IgM in 46.15 percent. Conclusions: HPA antibodies, mostly of the IgG class and directed to antigens present in the GP-IIb/IIIa complex, are common in Cuban patients awaiting kidney transplantation(AU)

Human Platelet Antigens in Brazilian Multiethnic Populations: Occurrence of Regional Variation and Frequency in a Large Urban Center (Belo Horizonte).

BACKGROUND: The frequency of human platelet antigens (HPA) varies according to ethnicity, which causes differences in the morbidity of alloimmune and autoimmune thrombocytopenic disorders in different populations. Studies on HPA frequencies in Brazil have reported differences among Brazilian populations produced by the diverse degrees of admixture throughout the country. METHODS: In the present study, we investigated the variation of HPA distribution in Brazil, compared with worldwide populations, and describe the frequencies of HPA-1, -2, -3, -5, and -15 in a large urban center in Southern Brazil (Belo Horizonte) based on a sample of blood donors. RESULTS: The principal component analysis and the dendrogram based on genetic distance revealed a clear relationship between Brazilian populations and the groups formed by European and African populations. The coefficients of variation for HPA allele frequencies suggest that Brazilian populations presented variations for HPA alleles comparable with the populations from continental groups. In Belo Horizonte, the allele a frequencies for HPA-1, -2, -3, -5 and -15 were 0.8575, 0.8400, 0.6225, 0.8525 and 0.5825 respectively. The genotypes with higher frequencies were a/a (72-74%), except for HPA-3 and -15, whose heterozygous a/b genotypes were shown to be more prevalent (43.5 and 44.5%, respectively). CONCLUSION: We confirmed the heterogeneity of HPA antigens in Brazilian populations, reinforcing the importance of HPA panels composed of regional blood donors, or a national panel that contemplates the specificities of the different regions of the country, in order to provide support in platelet transfusions and to minimize the risks associated with HPA alloimmunization. The evaluation of HPA data from Belo Horizonte represents the initial step toward the development of a genotyped platelet donor registry in order to treat HPA alloimmunized patients in this region.

Frequency of human platelet antigens (HPA)-1, -2, -5 and -15 in Brazilian blood donors and establishment of a panel of HPA-typed donors.

OBJECTIVES: The aim of this study is to keep a record of regular human platelet antigens (HPA)-typed blood donors and to compare their allele frequencies with those reported in other populations. BACKGROUND: HPA are polymorphisms expressed on platelet membrane glycoproteins. They can generate an immune response leading to platelet alloimmunisation that may show clinical manifestations, such as neonatal alloimmune thrombocytopenia, post-transfusion purpura and platelet refractoriness. Platelet alloimmunisation is not uncommon, therefore, for an optimum management, it is advantageous to establish a panel of typed platelets to help matched platelets selection in HPA-alloimmunised patients transfusion. METHODS: The polymerase chain reaction (PCR)-allele-specific primers and PCR-restriction fragment length polymorphism methods were used to determine the genotypes of HPA-1, -2, -5 and -15 systems of 337 blood donors. RESULTS: The three genotypes (AA, AB and BB) were found in all HPA systems analysed, and the most frequent genotypes were AA for HPA-1, -2 and -5 systems (mean: 0·732) and AB for HPA-15 system (mean: 0·523). Allele frequencies were 0·148, 0·155, 0·140 and 0·430 for HPA-1b, -2b, -5b and -15b, respectively, and they were similar to those found in Caucasian populations, especially for HPA-1. However, the B allele was more frequent in all HPA systems when compared with Amazon Indians, and the frequency of the B allele in our study was higher in HPA-1 and -15 systems and lower in HPA-2 and -5 systems in comparison with sub-Saharan African populations. CONCLUSIONS: A record of HPA-typed donors would enable rapid identification and selection of donors when HPA-compatible platelets are required for transfusion.

Frequency of human platelet antigens in oncohematological patients with thrombocytopenia and the probability of incompatibility to platelet transfusions.

OBJECTIVE: The objective of this study was to evaluate the frequencies of human platelet antigens in oncohematological patients with thrombocytopenia and to analyze the probability of their incompatibility with platelet transfusions. METHODS: Platelet antigen genotyping was performed by sequence-specific primer polymerase chain reaction (SSP-PCR) for the HPA-1a, HPA-1b, HPA-2a, HPA-2b, HPA-3a, HPA-3b, HPA-4a, HPA-4b, HPA-5a, HPA-5b; HPA-15a, HPA-15b alleles in 150 patients of the Hematology Service of the Hospital das Clínicas (FMUSP). RESULTS: THE ALLELE FREQUENCIES FOUND WERE: HPA-1a: 0.837; HPA-1b: 0.163; HPA-2a: 0.830; HPA-2b: 0.170; HPA-3a: 0.700; HPA-3b: 0.300; HPA-4a: 1; HPA-4b: 0; HPA-5a: 0.887; HPA-5b: 0.113; HPA-15a: 0.457 and HPA-15b: 0.543. CONCLUSIONS: Data from the present study showed that the A allele is more common in the population than the B allele, except for HPA-15. This suggests that patients homozygous for the B allele are more predisposed to present alloimmunization and refractoriness to platelet transfusions by immune causes. Platelet genotyping could be of great value in the diagnosis of alloimmune thrombocytopenia and to provide compatible platelet concentrates for these patients.

Frequency of human platelet antigens in oncohematological patients with thrombocytopenia and the probability of incompatibility to platelet transfusions

OBJECTIVE: The objective of this study was to evaluate the frequencies of human platelet antigens in oncohematological patients with thrombocytopenia and to analyze the probability of their incompatibility with platelet transfusions. METHODS: Platelet antigen genotyping was performed by sequence-specific primer polymerase chain reaction (SSP-PCR) for the HPA-1a, HPA-1b, HPA-2a, HPA-2b, HPA-3a, HPA-3b, HPA-4a, HPA-4b, HPA-5a, HPA-5b; HPA-15a, HPA-15b alleles in 150 patients of the Hematology Service of the Hospital das Clínicas (FMUSP). RESULTS: The allele frequencies found were: HPA-1a: 0.837; HPA-1b: 0.163; HPA-2a: 0.830; HPA-2b: 0.170; HPA-3a: 0.700; HPA-3b: 0.300; HPA-4a: 1; HPA-4b: 0; HPA-5a: 0.887; HPA-5b: 0.113; HPA-15a: 0.457 and HPA-15b: 0.543. CONCLUSIONS: Data from the present study showed that the A allele is more common in the population than the B allele, except for HPA-15. This suggests that patients homozygous for the B allele are more predisposed to present alloimmunization and refractoriness to platelet transfusions by immune causes. Platelet genotyping could be of great value in the diagnosis of alloimmune thrombocytopenia and to provide compatible platelet concentrates for these patients.