Conjugação e validação de controle isotípico IgG1-FITC para uso em citometria de fluxo
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Data
2007-12-01
Autores
Golim, Márjorie de Assis [UNESP]
Deffune, Elenice [UNESP]
Rossi-Ferreira, Rosana [UNESP]
Oliveira, Ana Paula E. [UNESP]
Padovani, Carlos Roberto [UNESP]
Machado, Paulo Eduardo de Abreu [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Associação Brasileira de Hematologia e Hemoterapia e daSociedade Brasileira de Transplante de Medula Óssea
Resumo
Em meados da década de 50 iniciou-se o desenvolvimento da citometria de fluxo, tecnologia que permite verificar características físico-químicas de células ou partículas suspensas em meio fluido. Esta tecnologia utiliza anticorpos monoclonais marcados com fluorocromos como ferramenta de investigação em diversas análises e necessita de controles isotípicos para definição da região negativa (background). Estes controles são constituídos por imunoglobulinas de mesmo isotipo e fluorocromo dos anticorpos testes, sendo o isotiocianato de fluoresceína (FITC) o marcador fluorescente mais utilizado na conjugação de anticorpos. Os controles isotípicos têm como função definir a fluorescência inespecífica (células negativas) e as regiões fluorescentes (células positivas). No presente estudo foi selecionado anticorpo monoclonal murino (AcMm) dirigido contra antígeno eritrocitário canino, produzido no Laboratório de Anticorpos Monoclonais do Hemocentro de Botucatu, o qual reage positivamente com hemácias de cães, mas nunca com leucócitos humanos, tendo, portanto, potencial utilidade como controle negativo em citometria de fluxo. A purificação do AcMm da subclasse IgG1 foi feita por cromatografia de afinidade em Proteína-A Sepharose, e o controle da purificação realizado por eletroforese em géis de ágarose e poliacrilamida (SDS-PAGE). A imunoglobulina purificada foi conjugada ao FITC e filtrado em coluna de Sephadex G-25 para separação das proteínas marcadas e não-marcadas. O AcMm conjugado foi testado contra hemácias de cães, e o êxito da conjugação comprovado por testes de fluorescência, sendo a mediana de positividade de 94,70. Frente a leucócitos humanos a mediana de positividade foi 0,03 contra 0,50 dos reagentes comerciais. Os testes estatísticos não-paramétricos de Wilcoxon e correlação de Spearman comprovaram a eficiência e validam o controle isotípico produzido em comparação aos reagentes comerciais testados.
It was during the 1950's that the development of flow cytometry started, technology that allow to measure physiochemical characteristics of cells or suspended particles in fluid. This technology uses monoclonal antibodies labeled by fluorochromes as investigation tool in several analysis and needs isotype controls to define the negative region (background). These controls are constituted by immunoglobulins of the same isotype and fluorochrome from test antibodies, being fluorescein isothiocyanate (FITC) the most fluorescent marker used in antibody conjugations. The isotype controls have the function to define the unspecific fluorescence (negative cells) and the fluorescent regions (positive cells). In this study was selected monoclonal antibody (mAb) against canine erythrocyte antigen, produced in the Monoclonal Antibodies Laboratory - Blood Center of Botucatu, which reacts positively with dog red blood cells, but never with human leukocytes, having therefore, utility potential as negative control in flow cytometry. The purification mAb of IgG1 subclass was made by affinity chromatography in Sepharose Protein-A and the purification control was performed by electrophoresis in ágarose and polyacrylamide gels (SDS-PAGE). The purified immunoglobulin was conjugated to FITC and after was filtered in Sephadex G25 column to separation of labeled and unlabeled proteins. The conjugated mAb was tested against dog red blood cells and the conjugation success was verified by fluorescence tests, being the median positivity of 94.70. To the human leucocytes the positivity median was 0.03 against 0.50 of the commercial reagents. The nonparametric statistical tests of Wilcoxon and the correlation Spearman showed the efficiency and validate the isotype control produced in relation to the tested commercial reagents.
It was during the 1950's that the development of flow cytometry started, technology that allow to measure physiochemical characteristics of cells or suspended particles in fluid. This technology uses monoclonal antibodies labeled by fluorochromes as investigation tool in several analysis and needs isotype controls to define the negative region (background). These controls are constituted by immunoglobulins of the same isotype and fluorochrome from test antibodies, being fluorescein isothiocyanate (FITC) the most fluorescent marker used in antibody conjugations. The isotype controls have the function to define the unspecific fluorescence (negative cells) and the fluorescent regions (positive cells). In this study was selected monoclonal antibody (mAb) against canine erythrocyte antigen, produced in the Monoclonal Antibodies Laboratory - Blood Center of Botucatu, which reacts positively with dog red blood cells, but never with human leukocytes, having therefore, utility potential as negative control in flow cytometry. The purification mAb of IgG1 subclass was made by affinity chromatography in Sepharose Protein-A and the purification control was performed by electrophoresis in ágarose and polyacrylamide gels (SDS-PAGE). The purified immunoglobulin was conjugated to FITC and after was filtered in Sephadex G25 column to separation of labeled and unlabeled proteins. The conjugated mAb was tested against dog red blood cells and the conjugation success was verified by fluorescence tests, being the median positivity of 94.70. To the human leucocytes the positivity median was 0.03 against 0.50 of the commercial reagents. The nonparametric statistical tests of Wilcoxon and the correlation Spearman showed the efficiency and validate the isotype control produced in relation to the tested commercial reagents.
Descrição
Palavras-chave
Controle isotípico, citometria de fluxo, anticorpo monoclonal, isotiocianato de fluoresceína (FITC), Isotype control, flow cytometry, monoclonal antibody, fluorescein isothiocyanate (FITC)
Como citar
Revista Brasileira de Hematologia e Hemoterapia. Associação Brasileira de Hematologia e Hemoterapia e daSociedade Brasileira de Transplante de Medula Óssea, v. 29, n. 4, p. 361-368, 2007.