Authors
Abstract(s)
A presença de isoaglutininas anti-A e anti-B da classe IgG em concentrados plaquetários
pode conduzir a reacções transfusionais hemolíticas devido à transferência passiva destes
anticorpos, especialmente quando presentes em alto título. Não existe consenso acerca de
qual o título crítico, mas alguma literatura considera valores ≥256 como “alto título”. A
transferência passiva de isoaglutininas com significado clínico pode ocorrer após transfusão de
componentes sanguíneos com incompatibilidade ABO minor, ou seja, quando doentes do
grupo sanguíneo A, B ou AB são transfundidos com componentes sanguíneos do grupo O.
O principal objectivo deste trabalho é o de estabelecer o título de anti-A e anti-B da classe
IgG a partir do qual a transferência passiva destas isoaglutininas pode ter significado clínico,
após transfusão de Concentrados Plaquetários de Aférese (CP-A) do grupo O em doentes do
grupo sanguíneo A, B ou AB. Para tal, foram executados testes em duas etapas independentes
mas inter-relacionadas.
Entre 1 de Junho e 30 de Novembro de 2010, foram determinados manualmente os títulos
de anti-A1 e anti-B da classe IgG em todas as unidades de CP-A do grupo O (n=83), colhidos
no Serviço de Medicina Transfusional (SMT) do IPO-Porto, com base na metodologia de
hemaglutinação em gel, com reagentes e material comercializado pela Diamed®. Foram ainda
estudadas as amostras de doentes do grupo A, B ou AB transfundidos com os CP-A cujo título
tinha sido determinado (n=21). O Teste de Antiglobulina Directo (TAD) foi realizado em
amostras pré-transfusionais e em amostras até 24 horas após a transfusão destes
componentes. Nos casos de resultados positivos do TAD, foi determinada a classe do
anticorpo existente. Perante um anticorpo da classe IgG, foi realizado um eluado eritrocitário
para caracterizar o tipo de isoaglutinina (anti-A1 e/ou anti-B).
Nos 83 dadores, os títulos de anti-A1 variaram entre 8 (1,2%) e 2048 (2,4%), com o título
128 como o mais frequente (24,1%). Os títulos de anti-B variaram entre 2 (1,2%) e 1024
(4,8%), com 64 como o valor mais frequente (25,3%). Destes 83 dadores, 21 (25,3%)
apresentavam apenas altos títulos de anti-A1, 8 (9,6%) apresentavam apenas altos títulos de
anti-B e 7 (8,4%) apresentavam altos títulos de anti-A1 e anti-B em simultâneo. Do total de
dadores estudados, verificou-se que 36 (43,3%) eram dadores de “alto título” de isoaglutininas.
Das 21 amostras de doentes analisadas, 4 revelaram TAD Positivo por IgG após transfusão de
CP-A. Destas 4 amostras, apenas 1 revelou a presença de anti-A1 no eluado eritrocitário. Não
foi encontrada qualquer relação entre o título de isoaglutininas e a transição do TAD de
negativo a positivo, nem foram relatadas reacções transfusionais hemolíticas após transfusão
de CP-A do grupo O. Dos 21 casos, 76,2% responderam com aumento na contagem
plaquetária pós-transfusional.
Com este estudo, não foi possível determinar o título crítico de isoaglutininas anti-A1 e anti-
B a partir do qual a transferência passiva adquire significado clínico. No entanto, foi possível
identificar que 43,3% dos dadores apresentaram títulos de anti-A1 e/ou anti-B ≥256,
considerados como dadores de alto título.
The presence of IgG anti-A and anti-B isoagglutinins in platelet concentrates may lead to hemolytic transfusional reactions due to passive transfer of these antibodies, especially when present in high titer. No international consensus exists on the critical titer, but some literature considers titers ≥256 as high titer. The passive transfer of isoagglutinins may occur in blood component transfusions with ABO minor incompatibility, that is, when patients from blood groups A, B or AB receive transfusions from blood group O components. The main goal of this study was to establish the IgG anti-A1 and/or anti-B isoagglutinin titer from which the passive transfer of isoagglutinins may have clinical meaning, after the transfusion of blood group O Single Donor Platelets (O-SDP’s). The performance of two independent but related phases permited the study. Between the 1st of June and the 30th of November, 2010, the IgG anti-A1 and anti-B titers were manually determined on all the O-SDP’s donations (n=83) collected in Serviço de Medicina Transfusional (SMT) in IPO-Porto. Patients samples (n=21) of blood groups A, B or AB who received O-SDP’s transfusions (for logistic purposes) were also analyzed. The Direct Antiglobulin Test (DAT) was performed in pre-transfusional samples and samples collected 24 hours after transfusion. Observing positive DAT results, the class of the existing antibody was determined. When a positive result was achieved from the IgG antibody, an erythrocyte eluate was performed to characterize the isoagglutinin type (anti-A1 and/or anti-B). All the tests were based on the Gel Hemagglutination methodology, with reagents and other material commercialized by Diamed®. Of the 83 SDP donors, the IgG anti-A1 titers ranged from 8 (1.2%) to 2048 (2.4%), with 128 as the most frequent (24.1%). The IgG anti-B titers ranged from 2 (1.2%) to 1024 (4.8%), with 64 as the most frequent (25.3%). Of the 83 donors, 21 (25,3%) presented only anti-A1 high titers, 8 (9,6%) presented only anti-B high titers and 7 (8,4%) presented anti-A1 and anti-B high titers, simultaneously. Of the 83 donors, 36 (43,3%) were considered as “high titre” donors. Of the 21 samples analyzed, 4 revealed positive DAT by IgG after transfusion. Of these 4 samples, only 1 revealed the presence of anti-A1 on the Erythrocyte Eluate. No relation was found between the isoagglutinins titer and the transition from negative to positive DAT after the O-SDP transfusion. No hemolytic transfusional reactions were reported after the transfusion. Of the 21 cases, 76.2% responded with an increase of the platelets number. From this study, it was not possible to determine anti-A1 and anti-B isoagglutinins critical titres from which the passive transfer may have clinical significance. However, it was possible to identify that 43,3% of the donors presented titers ≥256 of IgG anti-A1 and/or anti-B, considered as high titer donors
The presence of IgG anti-A and anti-B isoagglutinins in platelet concentrates may lead to hemolytic transfusional reactions due to passive transfer of these antibodies, especially when present in high titer. No international consensus exists on the critical titer, but some literature considers titers ≥256 as high titer. The passive transfer of isoagglutinins may occur in blood component transfusions with ABO minor incompatibility, that is, when patients from blood groups A, B or AB receive transfusions from blood group O components. The main goal of this study was to establish the IgG anti-A1 and/or anti-B isoagglutinin titer from which the passive transfer of isoagglutinins may have clinical meaning, after the transfusion of blood group O Single Donor Platelets (O-SDP’s). The performance of two independent but related phases permited the study. Between the 1st of June and the 30th of November, 2010, the IgG anti-A1 and anti-B titers were manually determined on all the O-SDP’s donations (n=83) collected in Serviço de Medicina Transfusional (SMT) in IPO-Porto. Patients samples (n=21) of blood groups A, B or AB who received O-SDP’s transfusions (for logistic purposes) were also analyzed. The Direct Antiglobulin Test (DAT) was performed in pre-transfusional samples and samples collected 24 hours after transfusion. Observing positive DAT results, the class of the existing antibody was determined. When a positive result was achieved from the IgG antibody, an erythrocyte eluate was performed to characterize the isoagglutinin type (anti-A1 and/or anti-B). All the tests were based on the Gel Hemagglutination methodology, with reagents and other material commercialized by Diamed®. Of the 83 SDP donors, the IgG anti-A1 titers ranged from 8 (1.2%) to 2048 (2.4%), with 128 as the most frequent (24.1%). The IgG anti-B titers ranged from 2 (1.2%) to 1024 (4.8%), with 64 as the most frequent (25.3%). Of the 83 donors, 21 (25,3%) presented only anti-A1 high titers, 8 (9,6%) presented only anti-B high titers and 7 (8,4%) presented anti-A1 and anti-B high titers, simultaneously. Of the 83 donors, 36 (43,3%) were considered as “high titre” donors. Of the 21 samples analyzed, 4 revealed positive DAT by IgG after transfusion. Of these 4 samples, only 1 revealed the presence of anti-A1 on the Erythrocyte Eluate. No relation was found between the isoagglutinins titer and the transition from negative to positive DAT after the O-SDP transfusion. No hemolytic transfusional reactions were reported after the transfusion. Of the 21 cases, 76.2% responded with an increase of the platelets number. From this study, it was not possible to determine anti-A1 and anti-B isoagglutinins critical titres from which the passive transfer may have clinical significance. However, it was possible to identify that 43,3% of the donors presented titers ≥256 of IgG anti-A1 and/or anti-B, considered as high titer donors