Gel microcolumn assay (GMA) is a modified serological technique that has been used for ABO and Rh typing, direct antiglobulin test (DAT), detecting alloantibodies, red cell phenotyping, and other applications. However, for DAT, the role of GMA is controversial. The purpose of this large study was to compare the performance of the conventional tube test (CTT) to GMA for detecting potentially significant antibodies coating red blood cells in vivo. From January 1996 to May 2002, we performed DATs by GMA and CTT on 9,862 blood samples submitted to our reference laboratory, using LISS/Coombs cards (DiaMed-Latino America, Lagoa Santa-MG, Brazil) for GMA and polyspecific and monospecific anti-IgG reagents for CTT. Acid eluates were prepared from all positive DAT samples. The specificity of eluates was determined by GMA. We detected nonconcordant results in 2,079 out of 3,163 positive DATs (65.7%). All of these tests were only positive in GMA. Sensitivity and specificity for DATs was 100% and 83.0% for gel, and 50.7% and 97.8% for tube, respectively. Based on this study GMA showed to be more sensitive than CTT for detecting potentially significant antibodies coating red blood cells in vivo.

Anti-D titration is the first step in the evaluation of the RhD-sensitized patient. Traditionally, anti-D titration has been performed by tube agglutination. Gel microcolumn assay is a method that has gained widespread usage throughout the world, mainly for ABO/Rh typing, unexpected antibody screening and direct antiglobulin tests. As gel assay has become widely used as a routine method to detect red blood cell alloantibodies, a critical anti-D titer needs to be established. Seventy-nine known blood samples with anti-D (titers 1-32) were titrated simultaneously by the conventional tube test and the gel microcolumn assay. Red blood cells (R0r phenotype) were used, with a final concentration of 3% for tube and 0.8% for gel. Serial twofold dilutions (2-2.048) were prepared for each technique, followed by reading in antiglobulin phase. Anti-D titration in the gel microcolumn assay showed significantly higher titers (mean 3.4-fold) than the conventional tube test in all samples studied. Based on these data, it was not possible to determine a critical titer for anti-D titration by the gel microcolumn assay.

Anti-U is a rare red blood cell alloantibody that has been found exclusively in blacks. It can cause hemolytic disease of the newborn and hemolytic transfusion reactions. We describe the case of a female newborn presenting a strongly positive direct antiglobulin test due to an IgG antibody in cord blood. Anti-U was recovered from cord blood using acid eluate technique. Her mother presented positive screening of antibodies with anti-U identified at delivery. It was of IgG1 and IgG3 subclasses and showed a titer of 32. Monocyte monolayer assay showed moderate interaction of Fc receptors with maternal serum with a positive result (3.1%). The newborn was treated only with 48 hours of phototherapy for mild hemolytic disease. She recovered well and was discharged on the 4th day of life. We conclude that whenever an antibody against a high frequency erythrocyte antigen is identified in brown and black pregnant women, anti-U must be investigated.

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Este trabalho é dedicado: À minha amada mulher Mailin, que pela intensidade de sentimentos transformou minha vida e que me mostra a todo momento viver com felicidade. Ao meu filho Ruryk, que mora no meu coração e é motivo de orgulho e alegria. À minha mãe Rose e ao meu pai Jorge, que foram exemplos para a formação do meu caráter, ensinando-me o valor da honestidade e do trabalho. À minha querida tia Thais, que nunca mediu esforços para fazer o bem; presença marcante na minha caminhada até aqui. AGRADECIMENTOS À Profa Dra. Márcia Cristina Zago Novaretti, grande estudiosa, colecionadora de inigualável experiência em imuno-hematologia, pela orientação, incentivo e tolerância. Ao Prof. Dr. Dalton de Alencar Fischer Chamone, por criar todas as condições para o aprimoramento científico e pela oportunidade na realização desse trabalho. Ao Prof. Dr. Pedro Enrique Dorlhiac-Llacer, pelo exemplo de profissionalismo e estímulo para o desenvolvimento científico.

Background: Alloantibody and autoantibody formation to red blood cell (RBC) antigens is one of the observed complications in sickle cell disease patients (SCD). The incidence of alloimmunization and autoantibodies in this selected group of patients is particularly high, although the clinical implication of autoantibodies in sickle cell disease patients is not clear. The purpose of this study is to evaluate the rate of alloantibody and autoantibody formation in SCD patients. Study design and methods: A retrospective analysis of transfused sickle cell disease patients followed at Fundacao Pro-Sangue Hemocentro de Sao Paulo between 1988 and 2004 were retrieved. Data on transfusion history, were correlated with development of alloantibodies and autoantibodies. Results: The study group was composed by 43 sickle cell disease patients followed for a mean of 89 months (22–116). The number of RBC units transfused (mean) was 64 (4–208). The development of the first alloantibody was detected after a mean of 40 months (1–107) after the first transfusion in our institution. Out of these patients, 31 (72.1%) were identified with RBC alloantibodies; 9 of these patients (21%) had both allo and autoantibodies to RBC antigens, whereas 5 (55.6%) developed autoantibodies after alloimmunization. The one remainder had only autoantibodies. Conclusion: The alloimmunization rate was extremely high (72.1%) and can be partially explained because of the extended time of follow-up (mean of 89 months). Different from the literature the development of autoantibodies preceeded alloantibodies in 44.4%. The impact of this observation in clinical practice warrants further investigation.