Decreased Megakaryocytepoiesis and No Excess of Platelet Destruction in Myelodysplastic Syndrome Patients.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4616-4616
Author(s):  
Kazunori Murai ◽  
Tatsuo Oyake ◽  
Shugo Kowata ◽  
Mamiko Ishiguro ◽  
Shigeki Ito ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Myelodysplastic Syndrome ◽  
Mononuclear Cells ◽  
Flow Cytometric Analysis ◽  
Annexin V ◽  
Refractory Anemia ◽  
Double Positive ◽  
Platelet Destruction ◽  
Color Flow ◽  
Normal Controls

Abstract Myelodysplastic syndrome (MDS) is a malignant disorder of hematopoietic progenitor cells and characterize by peripheral blood cytopenias with normo- to hyper-cellular bone marrow (BM) and morphologically dysplastic changes. Thrombocytopenia is observed in approximately 50% of MDS. The underlying pathophysiology is not fully understood. We analyzed the megakaryocytopoiesis and thrombocytopoiesis state by several parameters, including % reticulated platelet (%RP), which indicated platelet production state, glycoalicine index (GCI), which indicated platelet destruction state, and serum thromopoietin (TPO) levels in 47 refractory anemia in myelodysplastic syndrome (MDS-RCMD) patients with platelet counts less than 100 x 109/L. Furthermore, apoptosis frequency of megakaryocyte progenitors was analyzed in several patients. In all patients, dysmegakaryocytopoiesis findings such as hypolobulated micromegakaryocyte, non-lobulated nuclei in all sizes, and multiple, widely-separated nuclei were observed. The megakaryocytes in BM was normal to decreased in number in 32 patients (70%). Plasma TPO levels were significantly higher (718.7±746.0 pg/ml, n=50) in MDS-RCMD, while they were less than 205.0 pg/ml in normal volunteers (68.3 ±65.3 pg/ml, n=32)(p< 0.01). The %RPs in MDS-RCMD and normal controls were similar (MDS-RCMD 1.7±0.9% vs control 1.2±0.6%), indicating that increased thrombocytopoiesis was not observed in MDS-RCMD, regardless of high TPO levels. GCI was similar to normal controls (MDS-RCMD, 1.5±1.3% vs controls, 1.6±0.3%), indicating no excess of platelet destruction. There was no correlation between %RP and GCI. These data strongly suggested that platelet life span be not shortend in MDS-RCMD. We have reported that excessive apoptosis of CD34(+) cells was observed in MDS patients in the previous ASH meetings. The three-color flow cytometric analysis of bone marrow mononuclear cells using PE labeled Annexin V, PerCP labeled anti-CD34 antibody and FITC labeled anti-CD41 antibody were carried out in 17 MDS-RCMD patients. Much higher frequency of apoptosis was observed in double positive cells for CD34 and CD41 (48.1%:13.4∼78.4%, median: range) in MDS-RCMD, compared to that in normal controls (7.7%: 4.4∼17.2%, median: range) (P<0.05). The frequency of apoptosis was not increased significantly in CD34(−)CD41(+) cells in MDS-RCMD patients (median: 6.9% ; 1.3∼21.5%), n=12), compared to those in normal controls (3.3%: 1.5∼8.1%, n=10). These data strongly suggested that the main cause of thrombocytopenia in MDS-RCMD should be apoptosis in megakaryocytes progenitors, followed by the decreased megakaryocytopoiesis.

Ineffective Hematopoiesis in Megaloblastic Anemia Is Associated with Higher Frequency of Apoptosis in Each Lineage Immature and Mature Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3601-3601
Author(s):  
Tatsuo Oyake ◽  
Shigeki Ito ◽  
Shugo Kowata ◽  
Kazunori Murai ◽  
Yoji Ishida
Keyword(s):  
Bone Marrow ◽  
Mononuclear Cells ◽  
Bone Marrow Cells ◽  
Megaloblastic Anemia ◽  
Flow Cytometric Analysis ◽  
Annexin V ◽  
Cell Number ◽  
Color Flow ◽  
Cd34 Cells ◽  
Normal Controls

Abstract A deficiency of Vitamin B12 is a major cause of megaloblastic anemia (MBA). Ineffective hematopoiesis is observed in MBA, characterized by cytopenia, bone marrow cells with dysplastic change and normal to hypercellularity. We reported that excessive apoptosis of each lineage CD34(+) cells was observed in myelodysplastic syndrome (MDS) in the last ASH meeting. In this study, we investigated the hypothesis that excessive apoptosis induced the ineffective hematopoiesis in MBA. We performed the three color flow cytometric analysis of bone marrow mononuclear cells in 12 MBA patients using PE labeled Annexin V, PerCP labeled anti-CD34 antibody and FITC labeled anti-each lineage antibody (anti-glycophorin A (GPA) antibody, anti-CD33 antibody and anti-CD41 antibody). The frequency of apoptosis in subpopulations of immature (CD34(+)) and each lineage (+) cells or those of mature (CD34(−)) and each lineage (+) cells were calculated as the ratio (%) of (cell number with Annexin V(+)) divided by (cell number in the subpopulation). The subpopulations include CD34(+)GPA(+) (immature erythroid), CD34(+)CD33(+) (immature myeloid), CD34(+)CD41(+) (immature megakaryocytic), CD34(−)GPA(+) (mature erythroid), CD34(−)CD33(+) (mature myeloid) and CD34(−)CD41(+) (mature megakaryocytic) cells. Much higher frequency of apoptosis was observed in each lineage CD34(+) cells in MBA (median: 23.8% (range: 10.8–43.6%) in erythroid, 43.5% (12.7–67.3%) in myeloid, 50.1% (21.0–64.1%) in megakaryocytic lineages, P&lt; 0.05, respectively, n=12), compared to those in normal controls (8.5% (1.5–9.9%) in erythroid, 8.5% (2.2–8.8%) in myeloid, 7.7% (4.4–9.3%) in megakaryocytic lineages, respectively, n=10). While, the relatively higher frequency of apoptosis was observed in each lineage CD34(−) cells in MBA patients (median: 15.9% (range: 5.1–20.6%) in erythroid, 16.4% (5.6–23.2%) in myeloid, 16.1% (10.2–24.8%) in megakaryocytic lineages, P&lt; 0.05, respectively, n=12), compared to those in normal controls (4.8% (1.3–6.6%) in erythroid, 2.2% (0.6–4.4%) in myeloid, 3.3% (1.5–7.1%) in megakaryocytic lineages, respectively, n=10). These results suggest that the excessive apoptosis occurs not only in CD34(+) but also in CD34(−) cells, which induces ineffective hematopoiesis in MBA. Figure 1. The frequency of apoptosis in CD34+ BM cells Figure 1. The frequency of apoptosis in CD34+ BM cells Figure 2. The frequency of apoptosis in CD34− BM cells Figure 2. The frequency of apoptosis in CD34− BM cells

scholarly journals Rapid discrimination of early CD34+ myeloid progenitors using CD45-RA analysis

Blood ◽  
1993 ◽  
Vol 81 (9) ◽  
pp. 2301-2309 ◽  
Author(s):  
G Fritsch ◽  
P Buchinger ◽  
D Printz ◽  
FM Fink ◽  
G Mann ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cord Blood ◽  
Mononuclear Cells ◽  
Flow Cytometric Analysis ◽  
Color Flow ◽  
Gm Csf ◽  
Cd34 Cells ◽  
Myeloid Progenitor Cells ◽  
Macrophage Colony ◽  
Rapid Discrimination

Mononuclear cells (MNC) isolated by density centrifugation of cord blood and healthy bone marrow, and of peripheral blood (PB) from patients treated with granulocyte-macrophage colony-stimulating factor (GM-CSF) or G-CSF after chemotherapy, were double-stained with anti CD34 monoclonal antibody (MoAb) (8G12) versus anti CD45, CD45-RB, CD45- RO, and CD45-RA, respectively, and analyzed by flow cytometry. In all specimens, CD34+ MNC co-expressed CD45 at a low level and the expression of CD45-RB was similar or slightly higher. Most CD34+ MNC were negative for CD45-RO, a weak coexpression was only seen in some bone marrow (BM) and blood samples. In contrast, CD45-RA could subdivide the CD34+ population into fractions negative, dim (+), and normal positive (++) for these subgroups, and typical staining patterns were observed for the different sources of hematopoietic cells: in BM, most CD34+ MNC were RA++. In PB, their majority was RA++ after G-CSF but RA+ or RA- after GM-CSF. In cord blood, the hematopoietic progenitors were mainly RA-/RO-. Semisolid culture of sorted CD34+ MNC showed that clusters and dispersed (late) colony-forming unit-GM (CFU- GM) originated from 34+/RA++ cells, while the 34+/RA- MNC formed compact and multicentric, both white and red colonies derived from early progenitors. Addition of 20 ng stem cell factor per milliliter of medium containing 34+/RA- cord blood MNC led to a change of many burst- forming unit-erythrocyte (BFU-E) to CFU-mix which was not, at least to this extent, seen in blood and BM. We conclude that early myeloid CD34+ cells are 45+/RA-. Because this population excludes 34+/19+ B cells and 33+ myeloid cells, both of which are RA++, two-color flow cytometric analysis using CD34 and CD45-RA facilitates the characterization and quantification of early myeloid progenitor cells.

Myelodysplastic Syndrome with Bone Marrow Hypoplasia Is Associated with Much Higher Frequency of Apoptosis in CD 34+ Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2370-2370
Author(s):  
Tatsuo Oyake ◽  
Shigeki Ito ◽  
Shugo Kowata ◽  
Kazunori Murai ◽  
Yoji Ishida
Keyword(s):  
Bone Marrow ◽  
Myelodysplastic Syndrome ◽  
Immunosuppressive Therapy ◽  
Flow Cytometric Analysis ◽  
Hematopoietic Cells ◽  
Dramatic Improvement ◽  
Color Flow ◽  
Cd34 Cells ◽  
The Difference ◽  
Complete Blood Counts

Abstract Myelodysplastic Syndrome (MDS) is a clonal disorder characterized by dysplastic changes and ineffective hematopoiesis. The ineffective hematopoiesis is considered as the results of excessive apoptosis of bone marrow (BM) hematopoietic cells. Recently, immunosuppressive therapy is effective in some hypoplastic MDS patients, resulting in the dramatic improvement of complete blood counts. To elucidate the difference between MDS patients with hypoplasia and normo/hyperplasia in BM, we measured the frequency of apoptosis in each lineage CD34+ BM cells in 35 MDS (12 RA patients with hypoplastic BM, 9 RA, 7 RAEB, and 7 RAEB-t patients with normo/hyperplastic BM) at diagnosis by three color flow cytometric analysis. Apototic cells were analyzed by PE labeled AnnexinV. The lineage cell population was identified as CD34+/GlycophorineA+, CD34+/CD33+, CD34+/CD41+, CD34−/GlycophorineA+, CD34−/CD33+ and CD34−/CD41+. In this study, the higher frequency of apoptosis was observed in each lineage CD34+ cells in all MDS patients (n=35, median: 32.2% (range: 6.3–80.5%) in erythroid, 38.0% (8.8–93.3%) in myeloid, 41.4% (10.2–78.4%) in megakaryocytic lineage, p&lt;0.05, respectively), compared to that in normal controls (n=10, 8.5% (1.5–9.9%) in erythroid, 8.5% (2.2–8.8%) in myeloid, 7.7% (4.4–9.3%) in megakaryocytic lineage, respectively). While much higher frequency of apoptosis was observed in each lineage CD34+ cells in hypoplastic MDS patients (n=12, 49.1% (31.2–80.5%) in erythroid, 66.0% (37.8–93.3%) in myeloid, 68.5% (43.4–78.4%) in megakaryocytic lineage, p&lt;0.05, respectively), compared to that in normo/hyperplastic MDS patients (n=23, 28.7% (6.3–69.4%) in erythroid, 30.0% (8.8–61.7%) in myeloid, 29.8% (10.2–58.1%) in megakaryocytic lineage, respectively). The increased frequency of apoptosis in each lineage CD34+ cells decreased after immunosuppressive therapy (n=5, 25.3% (19.8–36.4%) in erythroid, 35.2% (20.1–42.0%) in myeloid, 38.5% (30.6–47.9%) in megakaryocytic lineage, respectively). Our findings suggested that the excessive apoptosis occurred mainly in CD34+ cells in hypoplastic MDS as well as in non-hypoplastic MDS. Much more increased frequency of excessive apoptosis in CD34+ cells resulted in BM hypoplasia in hypoplastic MDS patients. This method is useful to evaluate quantitatively the ineffective hematopoiesis in BM hematopoietic cells.

scholarly journals Rapid discrimination of early CD34+ myeloid progenitors using CD45-RA analysis

Blood ◽  
1993 ◽  
Vol 81 (9) ◽  
pp. 2301-2309 ◽  
Author(s):  
G Fritsch ◽  
P Buchinger ◽  
D Printz ◽  
FM Fink ◽  
G Mann ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cord Blood ◽  
Mononuclear Cells ◽  
Flow Cytometric Analysis ◽  
Color Flow ◽  
Gm Csf ◽  
Cd34 Cells ◽  
Myeloid Progenitor Cells ◽  
Macrophage Colony ◽  
Rapid Discrimination

Abstract Mononuclear cells (MNC) isolated by density centrifugation of cord blood and healthy bone marrow, and of peripheral blood (PB) from patients treated with granulocyte-macrophage colony-stimulating factor (GM-CSF) or G-CSF after chemotherapy, were double-stained with anti CD34 monoclonal antibody (MoAb) (8G12) versus anti CD45, CD45-RB, CD45- RO, and CD45-RA, respectively, and analyzed by flow cytometry. In all specimens, CD34+ MNC co-expressed CD45 at a low level and the expression of CD45-RB was similar or slightly higher. Most CD34+ MNC were negative for CD45-RO, a weak coexpression was only seen in some bone marrow (BM) and blood samples. In contrast, CD45-RA could subdivide the CD34+ population into fractions negative, dim (+), and normal positive (++) for these subgroups, and typical staining patterns were observed for the different sources of hematopoietic cells: in BM, most CD34+ MNC were RA++. In PB, their majority was RA++ after G-CSF but RA+ or RA- after GM-CSF. In cord blood, the hematopoietic progenitors were mainly RA-/RO-. Semisolid culture of sorted CD34+ MNC showed that clusters and dispersed (late) colony-forming unit-GM (CFU- GM) originated from 34+/RA++ cells, while the 34+/RA- MNC formed compact and multicentric, both white and red colonies derived from early progenitors. Addition of 20 ng stem cell factor per milliliter of medium containing 34+/RA- cord blood MNC led to a change of many burst- forming unit-erythrocyte (BFU-E) to CFU-mix which was not, at least to this extent, seen in blood and BM. We conclude that early myeloid CD34+ cells are 45+/RA-. Because this population excludes 34+/19+ B cells and 33+ myeloid cells, both of which are RA++, two-color flow cytometric analysis using CD34 and CD45-RA facilitates the characterization and quantification of early myeloid progenitor cells.

Erythropoietin-dependent transformation of myelodysplastic syndrome to acute monoblastic leukemia

Blood ◽  
2001 ◽  
Vol 98 (12) ◽  
pp. 3492-3494 ◽  
Author(s):  
Udomsak Bunworasate ◽  
Hilal Arnouk ◽  
Hans Minderman ◽  
Kieran L. O'Loughlin ◽  
Sheila N. J. Sait ◽  
...  
Keyword(s):  
Myelodysplastic Syndrome ◽  
Bone Marrow Cells ◽  
Tritiated Thymidine ◽  
Flow Cytometric Analysis ◽  
Refractory Anemia ◽  
Laboratory Findings ◽  
Flow Cytometric ◽  
Acute Monoblastic Leukemia ◽  
Leukemia Cutis ◽  
Marrow Cells

Abstract Acute monoblastic leukemia (acute myeloid leukemia [AML], French-American-British type M5a) with leukemia cutis developed in a patient 6 weeks after the initiation of erythropoietin (EPO) therapy for refractory anemia with ringed sideroblasts. AML disappeared from both marrow and skin after the discontinuation of EPO. Multiparameter flow cytometric analysis of bone marrow cells demonstrated coexpression of the EPO receptor with CD45 and CD13 on the surface of blasts. The incubation of marrow cells with EPO, compared to without, resulted in 1.3- and 1.6-fold increases, respectively, in tritiated thymidine incorporation and bromodeoxyuridine incorporation into CD13+ cells. Clinical and laboratory findings were consistent with the EPO-dependent transformation of myelodysplastic syndrome (MDS) to AML. It is concluded that leukemic transformation in patients with MDS treated with EPO may be EPO-dependent and that management should consist of the discontinuation of EPO followed by observation, if clinically feasible.

scholarly journals The analysis of the long-term impact of SARS-CoV-2 on the cellular immune system in individuals recovering from COVID-19 reveals a profound NKT cell impairment

2020 ◽  
Author(s):  
jia liu ◽  
Xuecheng Yang ◽  
Hua Wang ◽  
Ziwei Li ◽  
Hui Deng ◽  
...  
Keyword(s):  
T Cells ◽  
Immune System ◽  
Cd8 T Cells ◽  
Mononuclear Cells ◽  
Annexin V ◽  
Double Positive ◽  
Peripheral Blood Mononuclear ◽  
Cellular Immune System ◽  
Cellular Immune

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects millions of people and killed hundred-thousands of individuals. While acute and intermediate interactions between SARS-CoV-2 and the immune system have been studied extensively, long-term impacts on the cellular immune system remained to be analyzed. Here, we comprehensively characterized immunological changes in peripheral blood mononuclear cells in 49 COVID-19 convalescent individuals (CI) in comparison to 27 matched SARS-CoV-2 unexposed individuals (UI). Despite recovery from the disease for more than 2 months, CI showed significant decreases in frequencies of invariant NKT and NKT-like cells compared to UI. Concomitant with the decrease in NKT-like cells, an increase in the percentage of Annexin V and 7-AAD double positive NKT-like cells was detected, suggesting that the reduction in NKT-like cells results from cell death months after recovery. Significant increases in regulatory T cell frequencies, TIM-3 expression on CD4 and CD8 T cells, as well as PD-L1 expression on B cells were also observed in CI, while the cytotoxic potential of T cells and NKT-like cells, defined by GzmB expression, was significantly diminished. However, both CD4 and CD8 T cells of CI showed increased Ki67 expression and were fully capable to proliferate and produce effector cytokines upon TCR stimulation. Collectively, we provide the first comprehensive characterization of immune signatures in patients recovering from SARS-CoV-2 infection, suggesting that the cellular immune system of COVID-19 patients is still under a sustained influence even months after the recovery from disease.

scholarly journals E-cadherin is functionally involved in the maturation of the erythroid lineage.

1995 ◽  
Vol 131 (1) ◽  
pp. 243-249 ◽  
Author(s):  
S Armeanu ◽  
H J Bühring ◽  
M Reuss-Borst ◽  
C A Müller ◽  
G Klein
Keyword(s):  
Bone Marrow ◽  
Mononuclear Cells ◽  
Bone Marrow Cells ◽  
Cell Lineage ◽  
Unexpected Finding ◽  
Color Flow ◽  
Pcr Screening ◽  
Maturation Stages ◽  
Differentiation And Proliferation ◽  
E Cadherin

Differentiation and proliferation of hematopoietic progenitors take place in the bone marrow and is a tightly controlled process. Cell adhesion molecules of the integrin and immunoglobulin families have been shown to be involved in these processes, but almost nothing was known about the involvement of the cadherin family in the hematopoietic system. A PCR screening of RNA of human bone marrow mononuclear cells with specific primers for classical cadherins revealed that E-cadherin, which is mainly expressed by cells of epithelial origin, is also expressed by bone marrow cells. Western blot analysis and immunofluorescence staining of bone marrow sections confirmed this unexpected finding. A more detailed analysis using immunoaffinity columns and dual color flow cytometry showed that the expression of E-cadherin is restricted to defined maturation stages of the erythropoietic lineage. Erythroblasts and normoblasts express E-cadherin, mature erythrocytes do not. A functional role of E-cadherin in the differentiation process of the erythroid lineage was indicated by antibody-inhibition studies. The addition of anti-E-cadherin antibody to bone marrow mononuclear cultures containing exogeneous erythropoietin drastically diminished the formation of erythropoietic cells. These data suggest a non-anticipated expression and function of E-cadherin in one defined hematopoietic cell lineage.

Stimulation of Hematopoiesis by Amifostine in Patients With Myelodysplastic Syndrome

Blood ◽  
1997 ◽  
Vol 90 (9) ◽  
pp. 3364-3369 ◽  
Author(s):  
Alan F. List ◽  
Farah Brasfield ◽  
Ruth Heaton ◽  
Betty Glinsmann-Gibson ◽  
Linda Crook ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Myelodysplastic Syndrome ◽  
Dose Schedule ◽  
Treatment Withdrawal ◽  
Red Blood Cell Transfusion ◽  
Refractory Anemia ◽  
Hematopoietic Progenitors ◽  
Absolute Increase ◽  
Hematological Effects

Abstract The aminothiol, amifostine (Ethyol; U.S. Bioscience, West Conshohocken, PA), is a cytoprotective agent that ameliorates the toxicities of anticancer therapy. In vitro, amifostine promotes the formation and survival of primitive hematopoietic progenitors derived from myelodysplastic bone marrow (BM) specimens. To evaluate the hematological effects of amifostine, 18 patients with myelodysplastic syndrome (MDS) and one or more refractory cytopenias received treatment with amifostine in a Phase I/II study. Four cohorts received intravenous treatment with 100, 200, or 400 mg/m2 amifostine three times a week, or 740 mg/m2 weekly for three consecutive weeks followed by 2 weeks observation. Nonresponding patients received a second course of therapy at the next higher dose level depending upon drug tolerance. Bone marrow (BM) progenitor growth was assessed before treatment and after day 21. Diagnoses included refractory anemia (7), refractory anemia with ringed sideroblasts (5), refractory anemia with excess blasts (RAEB) (4), and RAEB-in transformation (RAEB-t) (2). Single- or multi-lineage hematologic responses occurred in 15 patients (83%) treated with the three-times-a-week dose schedule. Fourteen patients had a 50% or greater increase in absolute neutrophil count with amifostine treatment (range, 426 to 11,348/μL). Platelet count increased in 6 (43%) of 14 patients with thrombocytopenia (absolute increase, 16,000 to 110,000/μL), and 5 of 15 red blood cell transfusion-dependent patients had a 50% of greater reduction in transfusion needs. Assayable hematopoietic progenitors increased in 13 of 15 evaluable patients; including CFU-GEMM (12), BFU-E (8), and CFU-GM (6). Amifostine doses less than or equal to 200 mg/m2 were well tolerated, whereas grade II nausea, vomiting, and fatigue was limiting at higher doses. Three patients with excess blasts before enrollment experienced an increase in BM blast percentage and two patients had evolution to acute leukemia that persisted after treatment withdrawal. We conclude that amifostine administered at doses ≤200 mg/m2 three times a week is well tolerated and has hematologic activity in patients with MDS.

Characteristics of De Novo Acute Leukemia Patients with Glycosylphosphatidylinositol (GPI) Protein-Negative Population of Leukemic Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4462-4462
Author(s):  
Hideyoshi Noji ◽  
Tsutomu Shichishima ◽  
Masatoshi Okamoto ◽  
Kazuhiko Ikeda ◽  
Akiko Nakamura ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Leukemia ◽  
De Novo ◽  
Bone Marrow Failure ◽  
Flow Cytometric Analysis ◽  
Leukemic Cells ◽  
Remission Induction ◽  
Color Flow ◽  
Flow Cytometric ◽  
Number Of Patients

Abstract Paroxysmal nocturnal hemoglobinuria (PNH) is considered to be an acquired stem cell disorder affecting all hematopoietic lineages, which lack GPI-anchored membrane proteins, such as CD59, because of abnormalities in the phosphatidylinositol glycan-class A (PIG-A) gene. Also, PNH is one disorder of bone marrow failure syndromes, including aplastic anemia and myelodysplastic syndrome, which are considered as pre-leukemic states. In this study, to know some characteristics of patients with de novo acute leukemia, we investigated expression of CD59 in leukemic cells from 25 patients (female: male=8: 17; mean age ± standard deviation, 57.8 ± 19.5 years) with de novo acute leukemia by single-color flow cytometric analysis. In addition, the PIG-A gene from CD59− leukemic cells sorted by FACS Vantage in 3 patients with acute leukemia was examined by sequence analysis. All the patients had no past history of PNH. Based on the French-American-British criteria, the diagnosis and subtypes of acute leukemia were determined. The number of patients with subtypes M1, M2, M3, M4, M5, and M7 was 1, 14, 2, 4, 2, and 2, respectively. Two of the patients were classified into acute myeloid leukemia with trilineage myelodysplasia from morphological findings in bone marrow. Chromosomal analyses presented abnormal karyotypes in 14 of 25 patients. Flow cytometric analyses showed that leukemic cells from 16 of 25 patients (64%) had negative populations of CD59 expression and the proportion of the populations was 63.3 ± 25.7%, suggesting the possibility that CD59− leukemic cells from patients with de novo acute leukemia might be derived from PNH clones. In fact, the PIG-A gene analyses showed that monoclonal or oligoclonal PIG-A mutations in coding region were found in leukemic cells from 3 patients with CD59− leukemic cells and all of the clones with the PIG-A mutations were minor. Then, various clinical parameters, including rate of complete remission for remission-induction chemotherapy, peripheral blood, bone marrow blood, and laboratory findings, and results of chromosomal analyses were statistically compared between 2 groups of patients with (n=16) and without (n=9) CD59− leukemic cells. The reticulocyte counts (10.5 ± 13.0 x 104/μl) and proportions of bone marrow erythroblasts (17.5 ± 13.9%) in patients with only CD59+ leukemic cells were significantly higher than those (2.5 ± 1.7 x 104/μl, p&lt;0.05; and 5.6 ± 6.2%, p&lt;0.01, respectively) in patients with CD59− leukemic cells. The proportions of bone marrow blasts (69.3 ± 21.1%) in patients with CD59− leukemic cells were significantly higher than those (45.5 ± 19.3%, p&lt;0.02) in patients with only CD59+ leukemic cells. In conclusion, our findings indicate that leukemic cells derived from PNH clones may be common in de novo acute leukemia patients, suggesting that bone marrow failure may have already occurred in localized bone marrow even in de novo acute leukemia.

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