Comparison of microRNA expression in high-count monoclonal B-cell lymphocytosis and Binet A chronic lymphocytic leukemia

Abstract Background Evidence suggests that monoclonal B-cell lymphocytosis precedes all chronic lymphocytic leukemia cases, although the molecular mechanisms responsible for disease progression are not understood. Aberrant miRNA expression may contribute to the pathogenesis of chronic lymphocytic leukemia. The objective of this study was to compare miRNA expression profiles of patients with Binet A chronic lymphocytic leukemia with those of subjects with high-count monoclonal B-cell lymphocytosis and healthy volunteers (controls). Methods Twenty-one chronic lymphocytic leukemia patients, 12 subjects with monoclonal B-cell lymphocytosis and ten healthy volunteers were enrolled in this study. Flow cytometry CD19+CD5+-based cell sorting was performed for the chronic lymphocytic leukemia and monoclonal B-cell lymphocytosis groups and CD19+ cells were sorted to analyze the control group. The expressions of miRNAs (miR-15a, miR-16-1, miR-29b, miR-34a, miR-181a, miR-181b and miR-155) were determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Results Significant differences between the expressions in the chronic lymphocytic leukemia and monoclonal B-cell lymphocytosis groups were restricted to the expression of miR-155, which was higher in the former group. A comparison between healthy controls and monoclonal B-cell lymphocytosis/chronic lymphocytic leukemia patients revealed higher miR-155 and miR-34a levels and lower miR-15a, miR-16-1, miR-181a and miR-181b in the latter group. Conclusions Our results show a progressive increase of miR-155 expression from controls to monoclonal B-cell lymphocytosis to chronic lymphocytic leukemia. The role of miR-155 in the development of overt chronic lymphocytic leukemia in individuals with monoclonal B-cell lymphocytosis must be further analyzed.

Telomere length analysis in monoclonal B-cell lymphocytosis and chronic lymphocytic leukemia Binet A

Monoclonal B-cell lymphocytosis (MBL) is an asymptomatic clinical entity characterized by the proliferation of monoclonal B cells not meeting the diagnosis criteria for chronic lymphocytic leukemia (CLL). MBL may precede the development of CLL, but the molecular mechanisms responsible for disease progression and evolution are not completely known. Telomeres are usually short in CLL and their attrition may contribute to disease evolution. Here, we determined the telomere lengths of CD5+CD19+ cells in MBL, CLL, and healthy volunteers. Twenty-one CLL patients, 11 subjects with high-count MBL, and 6 with low-count MBL were enrolled. Two hundred and sixty-one healthy volunteers aged 0 to 88 years were studied as controls. After diagnosis confirmation, a flow cytometry CD19+CD5+-based cell sorting was performed for the study groups. Telomere length was determined by qPCR. Telomere length was similar in the 3 study groups but shorter in these groups compared to normal age-matched subjects that had been enrolled in a previous study from our group. These findings suggest that telomere shortening is an early event in CLL leukemogenesis.

Frequency of monoclonal B-cell lymphocytosis in relatives of patients with chronic lymphocytic leukemia / Frecuencia de linfocitosis monoclonal de células B en familiares de pacientes con leucemia linfoide crónica

Introduction: monoclonal B-cell lymphocytosis is a symptom free condition characterized by the circulation of small clonal population of B lymphocytes in peripheral blood (less than 5x10(9)/L) expressing an immunophenotype similar to chronic lymphocytic leukemia. Different studies based on big hospital series have manifested a higher risk in subjects with monoclonal B-cell lymphocytosis to progress to a chronic lymphocytic leukemia. The behavior of this hematologic entity is unknown therefore its frequency in sporadic chronic lymphocytic leukemia patient relatives was determined. Methods: transversal descriptive study, 8 color flow cytometry was performed using two of the tubes of the Euro Flow recommended panel, with modifications, for the diagnose of chronic lymphoproliferative disorders of B lymphocytes; besides, a fluorescence in situ hybridization was performed. univariate and bivariate analyses of the information were performed. Results: monoclonal B-cell lymphocytosis frequency found in 51 analyzed relatives was 2%, it was a female participant, 59 years old, with a total leukocyte count of 7.7x109/L and a B lymphocyte count of 0.124x10(9)/L; from these, 0.04x10(9)/L were clonal cells with restrictions of the kappa light chain. Rearrangements of the IGH gene (14q32) were found. Conclusion: monoclonal B-cell lymphocytosis was detected in one relative of a patient with sporadic chronic lymphocytic leukemia in a frequency similar to the one reported in general population.

Introducción: La linfocitosis monoclonal de células B es una condición asintomática que se caracteriza por la circulación de pequeñas poblaciones clonales de linfocitos B en sangre periférica (menos de 5x10(9)/L) que expresan un inmunofenotipo similar al de la leucemia linfoide cónica. Diferentes estudios basados en grandes series hospitalarias, han puesto de manifiesto un riesgo más elevado de los sujetos con linfocitosis monoclonal de células B de progresar a una leucemia linfoide crónica. En Colombia se desconoce el comportamiento de esta entidad hematológica, por tal razón se determinó su frecuencia en familiares de pacientes con leucemia linfoide crónica esporádica. Métodos: Estudio descriptivo transversal, se realizó citometría de flujo de 8 colores utilizando dos de los tubos del panel recomendado por Euro Flow para el diagnóstico de enfermedades linfoproliferativas crónicas de linfocitos B con modificaciones, además se hizo hibridación fluorescente in situ. Se realizó análisis univariado y bivariado. Resultados: La frecuencia de linfocitosis monoclonal de células B encontrada en los 51 familiares analizados fue del 2%, se trató de un participante del sexo femenino y 59 años de edad, con un recuento total de leucocitos de 7,7x10(9)/L y un recuento de linfocitos B de 0,124x109/L; de estos 0,04x10(9)/L eran células clonales con restricción de la cadena ligera kappa. Se encontraron reordenamientos del gen IGH (14q32). Conclusión: Se detectó linfocitosis monoclonal de células B en un familiar de paciente con leucemia linfoide cónica esporádica en una frecuencia similar a la informada en la población general.

Monoclonal B-cell lymphocytosis in individuals from sporadic (non-familial) chronic lymphocytic leukemia families persists over time, but does not progress to chronic B-cell lymphoproliferative diseases

BACKGROUND: Monoclonal B-cell lymphocytosis is classified as 'high-count or clinical' monoclonal B-cell lymphocytosis and 'low-count or population' monoclonal B-cell lymphocytosis. Previously, 167 first-degree relatives pertaining to sporadic (non-familial) chronic lymphocytic leukemia families were studied and the presence of seven monoclonal B-cell lymphocytosis individuals was reported.OBJECTIVE: The aim of this report is to describe the outcomes of five of the original monoclonal B-cell lymphocytosis individuals.METHODS: Flow cytometry analysis was performed on mononuclear cells previously isolated from peripheral blood samples. A strategy of sequential gating designed to identify the population of CD19+/CD5+ B-lymphocytes was used and, subsequently, the monoclonal B-cell lymphocytosis cells were characterized by the CD20weak/CD79bweak/negative phenotype.RESULTS: The monoclonal B-cell lymphocytosis clone showed consistent stability over time with little variations in size. After a median follow-up of 7.6 years, none of the five monoclonal B-cell lymphocytosis individuals progressed to chronic lymphocytic leukemia or other B-cell lymphoproliferative disease.CONCLUSIONS: The data of this study suggest that chronic lymphocytic leukemia-like monoclonal B-cell lymphocytosis detected in the context of sporadic chronic lymphocytic leukemia families is not prone to clinical evolution and could be just a sign of immune senescence.