Fatores de risco para aloimunização em pacientes com anemia falciforme / Risk factors for alloimmunization in patients with sickle cell anemia

OBJETIVO: Determinar a imunofenotipagem eritrocitária em doadores de sangue e em pacientes com anemia falciforme (SS) atendidos no Hemocentro de Alagoas e descrever a frequência e os fatores associados à aloimunização eritrocitária. MÉTODOS: Estudo transversal com 102 pacientes SS e 100 doadores de sangue. Realizou-se a fenotipagem eritrocitária, teste de Coombs Direto e Indireto e detecção de anticorpos irregulares por painel de hemácias fenotipadas. Os dados foram comparados por meio do teste de Mann-Whitney, qui-quadrado ou teste exato de Fisher. Para análise dos fatores associados à aloimunização utilizou-se a regressão logística univariada e múltipla. RESULTADOS: Os antígenos mais frequentes entre os pacientes e os doadores foram c, e, M, s, JK(a). Observaram-se diferenças significativas entre as frequências dos fenótipos dos pacientes e dos doadores em relação aos antígenos s, FY(a) e JK(b). Dos 79 pacientes transfundidos, 10 (12,7 por cento) apresentaram Coombs Indireto positivo. Detectaram-se 13 aloanticorpos, sete do sistema Rh, dois do Kell e quatro não identificados. Os fatores associados à aloimunização foram o intervalo de tempo entre a última transfusão e a data do teste e ter recebido mais de dez transfusões de hemácias. Receber mais de dez transfusões representou uma chance 16,39 (IC 95 por cento: 2,23-120,59) vezes maior de ser aloimunizado, em comparação aos que receberam menos que dez. CONCLUSÃO: A prevalência de aloimunização nos pacientes SS foi 12,7 por cento, sendo 70 por cento dos anticorpos encontrados pertencentes a grupos sanguíneos Rh e Kell. Este estudo mostra a importância da fenotipagem eritrocitária em doadores e receptores para diminuir o risco de aloimunização.

OBJECTIVE: To determine erythrocyte phenotyping in blood donors and patients with sickle cell anemia (SS) treated at Hemocentro of Alagoas and describe the frequency and factors associated with erythrocyte alloimmunization. METHODS: Cross-sectional study with 102 SS patients and 100 blood donors. The following tests were performed: erythrocyte phenotyping, Direct and Indirect antiglobulin test, and detection of irregular antibodies by panel of phenotyped red blood cells. Data were compared by Mann-Whitney, qui-square or Fisher’s exact tests. Factors associated with alloimmunization were studied by univariate and multiple logistic regression analysis. RESULTS: The most frequent antigens found in patients and blood donors were: c, e, M, s, JK(a). Significant differences were observed between the frequency of the phenotype of patients and donors in regard to antigens s, FY(a) and JK(b). Of 79 transfused patients, 10 presented positive Indirect Coombs. Thirteen alloantibodies were found, 7 of the Rh system, 2 of Kell and 4 were not identified. Factors associated with alloimmunization were the period of time between the last transfusion and the date of the test and more than 10 red blood cell transfusions. Patients who received more than 10 transfusions were 16.39 (95 percent CI: 2.23-120.59) times more likely to be alloimmunized than patients with fewer transfusions. CONCLUSION: The prevalence of alloimmunization in SS patients was 12.7 percent, with 70 percent of antibodies belonging to the Rh and Kell systems. This study shows the importance of performing erythrocyte phenotyping in blood donors and receptors to decrease the risk of alloimmunization.

Risk factors for alloimmunization by patients with sickle cell disease

Blood transfusion in patients with sickle cell disease (SCD) is limited by the development of alloantibodies to erythrocytes. In the present study, the frequency and risk factors for alloimmunization were determined. Transfusion records and medical charts of 828 SCD patients who had been transfused and followed at the Belo Horizonte Blood Center, Belo Horizonte, MG, Brazil, were retrospectively reviewed. Alloimmunization frequency was 9.9 percent (95 percent CI: 7.9 to 11.9 percent) and 125 alloantibodies were detected, 79 percent of which belonged to the Rhesus and Kell systems. Female patients developed alloimmunization more frequently (P = 0.03). The median age of the alloimmunized group was 23.3 years, compared to 14.6 years for the non-alloimmunized group (P < 0.0001). Multivariate analyses were applied to the data for 608 hemoglobin (Hb) SS or SC patients whose number of transfusions was recorded accurately. Number of transfusions (P = 0.00006), older age (P = 0.056) and Hb SC (P = 0.02) showed independent statistical associations with alloimmunization. Hb SC patients older than 14 years faced a 2.8-fold higher (95 percent CI: 1.3 to 6.0) risk of alloimmunization than Hb SS patients. Female Hb SC patients had the highest risk of developing alloantibodies. In patients younger than 14 years, only the number of transfusions was significant. We conclude that an increased risk of alloimmunization was associated with older patients with Hb SC, specially females, even after adjustments were made for the number of transfusions received, the most significant variable.

La placenta y el cordón umbilical del feto papiráceo en la anemia drepanocítica / The placenta and umbilical cord in papyraceous in sickle cell disease

Analizar la placenta y el cordón umbilical de un embarazo gemelar diamniónico-monocoriónico complicado con anemia de células falciformes y muerte intrauterina fetal es el propósito de este estudio. Análisis macro y microscópico de regiones de la placenta y del cordón umbilical del feto muerto fueron realizados, Inserción excéntrica del cordón, edema generalizado y colapso del mismo parecen ser la causa de muerte del feto papiráceo. Cambios degerativos fueron observados en el cordón umbilical y alteraciones placentarias demostraron una incrementada deposición de fobrinoide afectando el 40 por ciento de su disco placentario. Estos hallazgos son de importancia ya que la morbilidad del gemelo sobreviviente está en un alto riesgo. Como el síndrome de transfusión fetofetal ocurre en este tipo de placentación su posible aparición en los estadios tempranos del embarazo se discute en relación con otros factores que también son de elevado riesgo

Alteraçöes imunológicas em pacientes com anemia falciforme / Immunological disorders in sickle cell disease

Objetivos: Nosso objetivo foi revisar as alteraçöes imunológicas em pacientes com anemia falciforme, englobando as causas da maior susceptibilidade às infecçöes e o papel das moléculas de adesäo, citocinas e inflamaçäo sobre a aderência anormal das hemácias falciformes ao endotélio vascular. Métodos: Os artigos para revisäo foram obtidos a partir dos dados do MEDLINE, onde analisou-se a literatura, nos idiomas inglês e português, sobre anemia falciforme e moléculas de adesäo. Resultados: A freqüência de infecçöes por germes 0encapsulados é alta em pacientes com anemia falciforme, principalmente pelo Streptococcus pneumoniae. Isto se deve ao fato de que as crises vaso-oclusivas recorrentes no baço resultam na atrofia do órgäo, com conseqüente diminuiçäo de sua funçäo, principalmente a de opsonizaçäo. A adesäo anormal dos glóbulos vermelhos falciformes ao endotélio vascular mantém baixos níveis de isquemia tecidual. Conclusäo: Pacientes com anemia falciforme säo mais sensíveis a infecçöes, principalmente pneumocócicas, de modo que há necessidade de profilaxia antibiótica e vacinaçäo anti-pneumocócica. A melhor compreensäo dos defeitos imunológicos que predispöem à inflamaçäo e vasculite constantes, pode ser fundamental na escolha das drogas que devem ser utilizadas para diminuir as complicaçöes vasculares da anemia falciforme

Aspectos inmunologicos relacionados con la enfermedad por hemoglobinopatias / Immunologic aspects related to hemoglobinopathic diseases

The records of 96 patients with sickle cell disease were studied in relation to various immunological parameters. Age, sex, levels of total and fractionated serum protein and immunoglobulins, serum complements, antierythrocytic antibodies, circulating immune complexes, antiviral antibodies and lymphoid populations were taken into account. No major alterations in humoral immunity were found in this group of panamanian sickle cell patient

Serum immunoglobulins in sickle cell disease.

Immunoglobulins IgG, IgA and IgM were estimated in 20 cases of sickle cell disease in steady state, eleven cases of sickle cell disease in crisis and/or infection, 20 cases of sickle cell trait and 14 normal healthy controls. Immunoglobulin deficiency has not been observed in sickle cell disease. Significantly raised IgG but normal IgA and IgM found in sickle cell disease cases was probably due to chronic stimulation of reticuloendothelial cells secondary to chronic hemolysis. IgM levels were significantly higher in patients with splenic enlargement > 3 cm. There was no alteration in immunoglobulin levels in sickle cell trait.

Pattern of splenic phagocytic function in Brazilian patients with sickle cell disease

The splenic function measured by the counts of pitted erythrocytes has been assessed in 87 patients with sickle cell disease (59 homozygotes for hemoglobin S (SS), 14 double heterozygotes for Hb S and beta zero thalassemia (S/beta zero thal), 4 S/beta+ thal and 10 SC patients) in Southeast Brazil. Results showed a progressive increase in pit counts according to age. The reduction pattern in the splenic function was similar for the SS, S/beta zero thal and S/beta+ thal patients, and over the age of 12 almost all patients presented counts compatible with severe splenic hypofunction. Patients with SC hemoglobinopathy presented slower development of hyposplenism and lower levels of pit counts even in advanced ages. Except for S/beta+ thal patients, the developmental pattern of hyposplenism was not different from that reported among patients in the United States and Jamaica

Inmunodeficiencia celular asociada a la anemia drepanocitica / Cellular immunodeficiencia associated with sickle anemia

El estudio de la inmunidad celular en 38 pacientes adultos con anemia drepanocitica mostró una disminución significativa en el porcentaje de células formadoras de roseta espontánea y de linfocitos T reconocidos con un anticuerpo monoclonal anti-CD3. Esta alteración de las células T en sangre periférica al parecer ocurrió a expensas de la disminución de la subpoblación CD4+. Los estudios funcionales revelaron también una disminución significativa en la actividad de células citotóxicas naturales. Ninguno de los pacientes presentó anticuerpos contra los virus de la inmunodeficiencia humana tipo 1 y tipo 2 contra el HTLV-1 y el 60 %resultó seropositivo al citomegalovirus. No se encontró correlación entre las alteraciones detectadas y la presencia de anticuerpos contra este virus, el número de unidades de sangre transfundidas y el índice de infecciones anuales

Infecçöes e imunidade na doença falciforme

A incidência de infecçöes bacterianas em pacientes com doença falciforme, particularmente na anemia falciforme, é elevada. Pneumonia, diarréia, infecçäo do sistema urinário, osteomielite, septicemia e meningite ocorrem, principalmente, nos pacientes mais jovens. A base fisiopatológica para a maior suscetibilidade a infecçöes nesta doença é complexa. Aparentemente, a hipofunçäo esplênica constitui o componente principal, sendo acompanhada de anormalidades de opsonizaçäo, da via alternativa do complemento, produçäo de anticorpos, funçäo leucocitária e imunidade celular. A profilaxia dos episódios infecciosos deve ser feita com imunizaçäo antipneumocócica e uso de penicilina