RESUMEN
Adult T-cell leukemia/lymphoma (ATLL) patients have an extremely poor prognosis, partly due to their immunosuppressive state. The majority of ATLL patients have leukemic cells with phenotype similar to Tregs, prompting suggestions that ATLL cells themselves have immunosuppressive functions. In this study, we detected CD39 expression on ATLL cells, particularly frequent on aggressive subtypes. CD39 and CD73 convert extracellular adenosine triphosphate (ATP) into adenosine, a key player in Tregs' immunosuppression. In vitro culture, both CD39+ ATLL cells and normal Tregs converted rapidly extracellular ATP to AMP, which was disturbed by CD39 inhibitors, and was negated in the CD39 knockout MJ cell line. The proliferation of cocultured CD4+/CD8+ normal T cells was suppressed by CD39+ MJ cells, but not by CD39 knockout MJ cells. Supplemented ATP was exhausted by an EG7-OVA T-cell line with stable CD39 induction, but not by mock. When these cell lines were subcutaneously transplanted into murine flanks, Poly(I:C) peritoneal administration reduced tumor size to 1/3 in mock-transplanted tumors, but not in CD39 induced tumors. Overall, we found that ATLL cells express CD39 at a high rate, and our results suggest that this helps ATLL cells escape antitumor immunity through the extracellular ATPDase-Adenosine cascade. These findings will guide future clinical strategies for ATLL treatment.
Asunto(s)
Antígenos CD/genética , Apirasa/genética , Regulación Leucémica de la Expresión Génica , Tolerancia Inmunológica/genética , Inmunomodulación/genética , Leucemia-Linfoma de Células T del Adulto/genética , Leucemia-Linfoma de Células T del Adulto/inmunología , Adenosina Trifosfato/metabolismo , Animales , Antígenos CD/metabolismo , Apirasa/metabolismo , Biomarcadores , Línea Celular Tumoral , Modelos Animales de Enfermedad , Perfilación de la Expresión Génica , Técnicas de Silenciamiento del Gen , Xenoinjertos , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Inmunofenotipificación , Leucemia-Linfoma de Células T del Adulto/diagnóstico , Leucemia-Linfoma de Células T del Adulto/metabolismo , Ratones , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Subgrupos de Linfocitos T/patologíaRESUMEN
Although B lymphopoiesis is one of the best-defined paradigms in cell differentiation, our knowledge of the regulatory mechanisms underlying its earliest processes, in which hematopoietic stem cells (HSCs) enter the B lineage, is limited. However, recent methodological advances in sorting progenitor cells and monitoring their epigenetic features have increased our understanding of HSC activities. It is now known that even the highly enriched HSC fraction is heterogeneous in terms of lymphopoietic potential. While surface markers and reporter proteins provide information on the sequential differentiation of B-lineage progenitors, complex interactions between transcription factors have also been shown to play a major role in this process. Epigenetic regulation of histones, nucleosomes, and chromatin appears to play a crucial background role in this elaborate transcription network. In this review, we summarize recent findings on the physiological processes of early B-lineage differentiation, which provides a new paradigm for understanding the harmonious action of genetic and epigenetic mechanisms.
Asunto(s)
Diferenciación Celular/genética , Epigénesis Genética , Linfopoyesis/genética , Células Precursoras de Linfocitos B/citología , Células Precursoras de Linfocitos B/metabolismo , Animales , Linfocitos B/citología , Linfocitos B/metabolismo , Linfocitos B/patología , Médula Ósea/metabolismo , Linaje de la Célula/genética , Transformación Celular Neoplásica/genética , Cromatina/metabolismo , Citocinas/metabolismo , Humanos , Transducción de Señal , Factores de Transcripción/metabolismoRESUMEN
OBJECTIVES: To characterize and evaluate the validity of a novel coculture system for studying human B-lymphocyte developmental biology. MATERIALS AND METHODS: We developed a long-term culture system to produce B lymphocytes from human CD34(+) cells purified from umbilical cord blood using human mesenchymal stem cells (hMSC) as stroma. We evaluated the effects of several low molecular weight inhibitors, recombinant proteins, and neutralizing antibodies (Abs) as potential regulators of B-lymphocyte development. RESULTS: Our cocultures of 2000 CD34(+) cells in the presence of stem cell factor and Flt3-ligand produced 1-5 x 10(5) CD10(+) cells after 4 weeks of culture. Surface IgM(+) immature B cells began to appear after 4 weeks. We evaluated the negative-regulatory effects of the transforming growth factor (TGF)-beta superfamily on human B lymphopoiesis, and found that adding an anti-activin A antibody enhanced generation of CD10(+) cells two- to three-fold. As well, the proportion of CD10(+) cells in the generated cells increased markedly, indicating that activin A downregulated B lymphopoiesis more efficiently than myelopoiesis. Addition of TGF-beta1 suppressed B-lymphocyte production by 20% to 30%, while addition of an anti-bone morphogenetic protein (BMP)-4 antibody or recombinant BMP-4 had no effect. Therefore, the strength of ability to suppress human B lymphopoiesis seemed to be activin A > TGF-beta1 > BMP-4. None of these three factors influenced the emergence of IgM(+) cells. CONCLUSIONS: hMSC coculture supported human B lymphopoiesis. Activin A selectively suppressed B lymphocyte production.