Effects of human recombinant erythropoietin on differentiation and distribution of erythroid progenitor cells on murine medullary and splenic erythropoiesis during hypoxia and post-hypoxia.

Hemopoietic cells, the extracellular matrix, growth factors and the microenvironment are involved in the regulation of hemopoiesis. Although the regulation of erythropoiesis is well understood at the cellular level in vivo and in vitro, the role of hemopoietic sites of erythroid progenitors production has not been well defined in both steady state conditions and in stress erythropoiesis. In this study we examined the qualitative erythroid differentiation and quantitative changes of the erythroid progenitors in different erythropoietic organs during erythropoiesis of stress in a hypoxia-induced polycythemia and post-hypoxic changes in a mice model. Chronic intermittent exposure to hypobaric hypoxia induced polycythemia in mice and the post-hypoxic period was characterized by total suppression of erythropoiesis. The number and distribution in hemopoietic sites of Immature Erythroid Burst (BFU-EI), Mature Erythroid Burst (BFU-EM) and Erythroid Colony Forming Units (CFU-E) was evaluated in bone marrow and spleen of hypoxic and post-hypoxic mice after removal from the chamber. The number of BFU-EI and CFU-E, was evaluated in both femoral bone marrow and spleen of ex-hypoxic polycythemic mice, at two times intervals after the end of hypoxia. We found that in both bone marrow and spleen, the kinetics of the CFU-E pool was characterized by a sharp fall from above normal to lower than normal levels. BFU-EM increased from normal to higher than normal levels. These results have been correlated with both erythropoietin (EPO) and the erythropoietic activity. The results show that EPO levels largely control both the differentiation and the amplification of the CFU-E pool and they suggest that EPO may acts as a "survival factor" at the CFU-E level and/or increase the flow of cells from BFU-E to CFU-E. After the termination of the period of hypoxia and during post-hypoxia there was a reduction in EPO production which subsequently caused a depletion of the CFU-E population, indicating that the size of the CFU-E pool is EPO-dependent. After the injection of 1U of recombinant human erythropoietin (rHuEPO) the size of that pool was increased and the pool of BFU-EI was decreased. It is noteworthy that our studies show that the spleen functions as a large reservoir of erythroid precursors for hypoxia-induced stress erythropoiesis.

Impaired response of polycythemic mice to erythropoietin induced by protein starvation imposed after hormone administration.

The present study was performed to determine the stage of the erythropoietic pathway which is affected by starvation or protein deprivation and whose manifestation is a depressed response to exogenous erythropoietin (EPO). The response to recombinant human EPO was measured in post-hypoxic polycythemic mice by determination of 59Fe uptake into red cells, spleen and femur and/or erythroid colony forming units (CFU-E) and erythroid precursor cell concentrations in femoral marrow. Experimental mice were either starved or fed one of seven different diets whose protein (casein) content ranged from 0 to 20%. All diets were isocaloric. The response of mice maintained on the standard diet (Purina Lab chow) was taken as the normal one. Starvation during the 48-hour period immediately before EPO injection had no effect on the response to the hormone. Starvation, and protein deprivation to a lesser extent, during the 48-hour period following EPO, on the other hand, significantly reduced the response. There was a progressive increase in the response as the casein content of the diet was increased. A normal response was observed when dietary casein concentration was 10%. These findings indicate that nutritional deprivation or dietary protein alterations during the period immediately following EPO injection in polycythemic mice can have detrimental effects on the erythroid response in a model in which nutritional deprivation was relatively short and acute. They also indicate that the subnormal response is not due to a decreased size of the erythroid progenitor pool available for differentiation but to deficient rates of differentiation of erythropoietic units.

[T lymphoma of immature phenotype associated with polycythemia vera]. / Linfoma T de fenotipo inmaduro asociado a una policitemia vera.

A 20-year old patient is presented with generalized lymphadenopathy, splenomegaly, hyperleukocytosis and a bone marrow biopsy showing panmyelosis with predominance of immature granulocytes. Lymph node biopsy showed a histopathological feature that was diagnosed as a chronic granulocytic leukemia in blast crisis. The cell surface phenotype of these blast cells showed predominance of immature CD1+, CD7+ T lymphocytes. The T cell lineage was confirmed by DNA rearrangement studies. In addition, the patient showed erythrocytosis, arterial O2 saturation of 92% and thrombocytosis, characteristics of polycythemia vera. After chemotherapy, the patient relapsed with similar symptoms and lymph node cells of similar immature T phenotype. With a revised diagnosis of immature T cell lymphoma associated to a myeloproliferative disorder and polyglobulia, the patient received a combined treatment of Cyclophosphamide-Adriamycin-Vincristine-VM26-Prednisone. Two months later, the patient relapsed again. He received the first phase of induction of the BFM protocol, with partial clinical remission. Five months later, the patient returned with fever, polyadenopathy and splenomegaly. Lymph node cells showed again immature T cell phenotype. The patient was next treated with the m-BACOD scheme, with no response and progression of the disease and he died few days later due to massive bleeding and cardiorespiratory failure.

Linfoma T de fenotipo inmaduro asociado a una policitemia vera / T lymphoma of immature phenotype associated with polycythenia vera

Se presenta un paciente de 20 años con poliadenopatías, esplenomegalia hiperleucocitosis y una biopsia de médula ósea que mostró una panmielosis con predominio d eelementos inmaduros. El estudio histopatológico de la biopsia de un ganglio linfático sugirió el diagnóstico de leucemia mieloide crónica en crisis blástica. El fenotipo inmunológico de las células blásticas mostró predominio de celulas T con fenotipo inmaduro CS1+, CD7+. El linaje celular T se confirmó por estudios de reordenamiento genético. Presenta además eritrocitosis, saturación arterial de O2 de 92% y trombocitosis, características de policitemia vera. Luego de quimioterapia Vincristina y Prednisona, recae a los dos meses con síntomas similares y con células de ganglio linfático del mismo fenotipo T inmaduro. Se replantea el diagnóstico como linfoma T asociado a un síndrome mieloproliferativo y policitemia, y se lo trata con Ciclofosfamida-Vincristina-VM26-Prednisona. Luego de una segunda recaída, dos meses después, se le indica un protocolo BFM, al que responde parcialmente. Cinco meses después el paciente presenta una tercera recaída, donde las células de ganglio muestran nuevamente fenotipo T inmaduro. No responde a un tratamiento con esquema m-BACOD, la enfermedad progresa, falleciendo luego de una hemorragia masiva por un paro cardiorespiratorio (AU)

Linfoma T de fenotipo inmaduro asociado a una policitemia vera / T lymphoma of immature phenotype associated with polycythenia vera

Se presenta un paciente de 20 años con poliadenopatías, esplenomegalia hiperleucocitosis y una biopsia de médula ósea que mostró una panmielosis con predominio d eelementos inmaduros. El estudio histopatológico de la biopsia de un ganglio linfático sugirió el diagnóstico de leucemia mieloide crónica en crisis blástica. El fenotipo inmunológico de las células blásticas mostró predominio de celulas T con fenotipo inmaduro CS1+, CD7+. El linaje celular T se confirmó por estudios de reordenamiento genético. Presenta además eritrocitosis, saturación arterial de O2 de 92% y trombocitosis, características de policitemia vera. Luego de quimioterapia Vincristina y Prednisona, recae a los dos meses con síntomas similares y con células de ganglio linfático del mismo fenotipo T inmaduro. Se replantea el diagnóstico como linfoma T asociado a un síndrome mieloproliferativo y policitemia, y se lo trata con Ciclofosfamida-Vincristina-VM26-Prednisona. Luego de una segunda recaída, dos meses después, se le indica un protocolo BFM, al que responde parcialmente. Cinco meses después el paciente presenta una tercera recaída, donde las células de ganglio muestran nuevamente fenotipo T inmaduro. No responde a un tratamiento con esquema m-BACOD, la enfermedad progresa, falleciendo luego de una hemorragia masiva por un paro cardiorespiratorio

Linfoma T de fenotipo inmaduro asociado a una policitemia vera. / [T lymphoma of immature phenotype associated with polycythemia vera]

A 20-year old patient is presented with generalized lymphadenopathy, splenomegaly, hyperleukocytosis and a bone marrow biopsy showing panmyelosis with predominance of immature granulocytes. Lymph node biopsy showed a histopathological feature that was diagnosed as a chronic granulocytic leukemia in blast crisis. The cell surface phenotype of these blast cells showed predominance of immature CD1+, CD7+ T lymphocytes. The T cell lineage was confirmed by DNA rearrangement studies. In addition, the patient showed erythrocytosis, arterial O2 saturation of 92

and thrombocytosis, characteristics of polycythemia vera. After chemotherapy, the patient relapsed with similar symptoms and lymph node cells of similar immature T phenotype. With a revised diagnosis of immature T cell lymphoma associated to a myeloproliferative disorder and polyglobulia, the patient received a combined treatment of Cyclophosphamide-Adriamycin-Vincristine-VM26-Prednisone. Two months later, the patient relapsed again. He received the first phase of induction of the BFM protocol, with partial clinical remission. Five months later, the patient returned with fever, polyadenopathy and splenomegaly. Lymph node cells showed again immature T cell phenotype. The patient was next treated with the m-BACOD scheme, with no response and progression of the disease and he died few days later due to massive bleeding and cardiorespiratory failure.