Rapid Detection of SAP Deficiency in Cytotoxic Lymphocytes from Patients with X-Linked Lymphoproliferative Disease and Their Family Members.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3846-3846
Author(s):  
Yasuhiro Tabata ◽  
Joyce Villanueva ◽  
Susan M. Lee ◽  
Kejian Zhang ◽  
Hirokazu Kanegane ◽  
...  
Keyword(s):  
T Cells ◽  
Family History ◽  
Bone Marrow Failure ◽  
Family Members ◽  
Flow Cytometric Analysis ◽  
Lymphoproliferative Disease ◽  
Cytotoxic Lymphocytes ◽  
Diagnostic Laboratory ◽  
Color Flow ◽  
Clinical Syndromes

Abstract Background: X-linked lymphoproliferative disease (XLP) is a primary immunodeficiency, which is characterized by an extreme susceptibility to Epstein-Barr virus (EBV). In half of the XLP patients, primary EBV infection can be fatal with explosive activation and proliferation of lymphocytes in many organs, which leads to fluminant hepatitis and bone marrow failure with hemophagocytosis. Mutations in the SH2D1A gene, which encodes the SAP protein, have been described in a proportion of patients with the clinical syndrome of XLP. The diagnosis of XLP is still difficult given its clinical heterogeneity, and the lack of a readily available rapid diagnostic laboratory test, particularly in cases without a family history of XLP. XLP should always be a consideration in males with EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH). Methods: Four-color flow cytometric analysis was used to establish normal patterns of SAP expression for control subjects, and patterns of SAP staining in cytotoxic lymphocytes (CD8+ T cells, CD56+ T cells and natural killer [NK] cells). This assay was used to study patients with clinical syndromes consistent with XLP, and in some cases; their family members. Results: 6 patients with XLP confirmed by detection of mutations in the coding regions of SH2D1A showed lack of intracellular SAP in all cytotoxic cell types; one was tested presymptomatically. Carriers of SH2D1A mutations tested (mother and sister) had decreased SAP staining patterns below normal levels. Eleven males with clinical syndromes consistent with XLP, predominantly EBV-HLH who were demonstrated to have normal or increased perforin expression were also studied. All patients showed normal SAP expression including one case with a convincing X-linked family history; all were subsequently shown to have no mutations in SH2D1A. Additionally, one asymptomatic adult male with an intronic mutation previously published as causing XLP was found to have normal SAP expression. Conclusions: Four-color flow cytometry provides diagnostic information that may speed the identification of this fatal disease, differentiating it from other EBV-HLH. We also suspect it will prove useful in substantiating or excluding disease-causing genetic variants in the SH2D1A gene.

Rapid detection of intracellular SH2D1A protein in cytotoxic lymphocytes from patients with X-linked lymphoproliferative disease and their family members

Blood ◽  
2005 ◽  
Vol 105 (8) ◽  
pp. 3066-3071 ◽  
Author(s):  
Yasuhiro Tabata ◽  
Joyce Villanueva ◽  
Susan Molleran Lee ◽  
Kejian Zhang ◽  
Hirokazu Kanegane ◽  
...  
Keyword(s):  
Protein Expression ◽  
Flow Cytometric Analysis ◽  
Cell Types ◽  
Lymphoproliferative Disease ◽  
Clinical Syndrome ◽  
Cytotoxic Lymphocytes ◽  
Healthy Controls ◽  
Diagnostic Laboratory ◽  
Color Flow ◽  
Barr Virus

AbstractMutations in the SH2D1A gene have been described in most patients with the clinical syndrome of X-linked lymphoproliferative disease (XLP). The diagnosis of XLP is still difficult given its clinical heterogeneity and the lack of a readily available rapid diagnostic laboratory test, particularly in patients without a family history of XLP. XLP should always be a consideration in males with Epstein-Barr virus–associated hemophagocytic lymphohistiocytosis (EBV-HLH). Four-color flow cytometric analysis was used to establish normal patterns of SH2D1A protein expression in lymphocyte subsets for healthy subjects. Three of 4 patients with XLP, as confirmed by the detection of mutations in the SH2D1A gene, had minimal intracellular SH2D1A protein in all cytotoxic cell types. The remaining patient lacked intracellular SH2D1A protein in CD56+ natural killer (NK) and T lymphocytes and had an abnormal bimodal pattern in CD8+ T cells. Carriers of SH2D1A mutations had decreased SH2D1A protein staining patterns compared with healthy controls. Eleven males with clinical syndromes consistent with XLP, predominantly EBV-HLH, had patterns of SH2D1A protein expression similar to those of healthy controls. Four-color flow cytometry provides diagnostic information that may speed the identification of this fatal disease, differentiating it from other causes of EBV-HLH.

Perforin expression in cytotoxic lymphocytes from patients with hemophagocytic lymphohistiocytosis and their family members

Blood ◽  
2002 ◽  
Vol 99 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Kazuhiro Kogawa ◽  
Susan M. Lee ◽  
Joyce Villanueva ◽  
Daniel Marmer ◽  
Janos Sumegi ◽  
...  
Keyword(s):  
T Cells ◽  
Nk Cells ◽  
Cd8 T Cells ◽  
Hemophagocytic Lymphohistiocytosis ◽  
Family Members ◽  
The Other ◽  
Cytotoxic Lymphocytes ◽  
Color Flow ◽  
Cytotoxic Cells ◽  
Perforin Expression

Mutations in the perforin gene have been described in some patients with hemophagocytic lymphohistiocytosis (HLH), but the role of perforin defects in the pathogenesis of HLH remains unclear. Four-color flow cytometric analysis was used to establish normal patterns of perforin expression for control subjects of all ages, and patterns of perforin staining in cytotoxic lymphocytes (natural killer [NK] cells, CD8+ T cells, CD56+ T cells) from patients with HLH and their family members were studied. Eleven unrelated HLH patients and 19 family members were analyzed prospectively. Four of the 7 patients with primary HLH showed lack of intracellular perforin in all cytotoxic cell types. All 4 patients showed mutations in the perforin gene. Their parents, obligate carriers of perforin mutations, had abnormal perforin-staining patterns. Analysis of cytotoxic cells from the other 3 patients with primary HLH and remaining family members had normal percentages of perforin-positive cytotoxic cells. On the other hand, the 4 patients with Epstein-Barr virus–associated HLH typically had depressed numbers of NK cells but markedly increased proportions of CD8+ T cells with perforin expression. Four-color flow cytometry provides diagnostic information that, in conjunction with evidence of reduced NK function, may speed the identification of life-threatening HLH in some families and direct further genetic studies of the syndrome.

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<0.05; and 5.6 ± 6.2%, p<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<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.

scholarly journals Identification of an HLA-A*0201-Restricted T-Cell Epitope on the MPT51 Protein, a Major Secreted Protein Derived from Mycobacterium tuberculosis, by MPT51 Overlapping Peptide Screening

2008 ◽  
Vol 76 (4) ◽  
pp. 1565-1571 ◽  
Author(s):  
Taiki Aoshi ◽  
Toshi Nagata ◽  
Mina Suzuki ◽  
Masato Uchijima ◽  
Dai Hashimoto ◽  
...  
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Flow Cytometric Analysis ◽  
Cell Epitope ◽  
T Cell Epitope ◽  
Computer Algorithms ◽  
Dna Encoding ◽  
Color Flow ◽  
Ifn Γ

ABSTRACT CD8+ T cells play a pivotal role in protection against Mycobacterium tuberculosis infection. We identified a novel HLA-A*0201-restricted CD8+ T-cell epitope on a dominant secreted antigen of M. tuberculosis, MPT51, in HLA-A*0201 transgenic HHD mice. HHD mice were immunized with plasmid DNA encoding MPT51 with gene gun bombardment, and gamma interferon (IFN-γ) production by the immune splenocytes was analyzed. In response to overlapping synthetic peptides covering the mature MPT51 sequence, the splenocytes were stimulated to produce IFN-γ by only one peptide, p51-70. Three-color flow cytometric analysis of intracellular IFN-γ and cell surface CD4 and CD8 staining revealed that the MPT51 p51-70 peptide contains an immunodominant CD8+ T-cell epitope. Further analysis using computer algorithms permitted identification of a bona fide T-cell epitope, p53-62. A major histocompatibility complex class I stabilization assay using T2 cells confirmed that this epitope binds to HLA-A*0201. The T cells were capable of lysing MPT51 p53-62 peptide-pulsed T2 cells. In addition, MPT51 p53-62-specific memory CD8+ T cells were found in tuberculin skin test-positive HLA-A*0201+ healthy individuals. Use of this HLA-A*0201-restricted CD8+ T-cell epitope for analysis of the role of MPT51-specific T cells in M. tuberculosis infection and for design of vaccines against tuberculosis is feasible.

scholarly journals Impaired Differentiation of Highly Proliferative ICOS+-Tregs Is Involved in the Transition from Low to High Disease Activity in Systemic Lupus Erythematosus (SLE) Patients

2021 ◽  
Vol 22 (17) ◽  
pp. 9501
Author(s):  
Florian Kälble ◽  
Lisa Wu ◽  
Hanns-Martin Lorenz ◽  
Martin Zeier ◽  
Matthias Schaier ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
T Cells ◽  
Lupus Erythematosus ◽  
Costimulatory Molecule ◽  
Flow Cytometric Analysis ◽  
Significant Shift ◽  
Healthy Controls ◽  
Systemic Lupus ◽  
Color Flow ◽  
Active Disease

Dysregulations in the differentiation of CD4+-regulatory-T-cells (Tregs) and CD4+-responder-T-cells (Tresps) are involved in the development of active systemic lupus erythematosus (SLE). Three differentiation pathways of highly proliferative inducible costimulatory molecule (ICOS)+- and less proliferative ICOS−-CD45RA+CD31+-recent-thymic-emigrant (RTE)-Tregs/Tresps via CD45RA−CD31+-memory-Tregs/Tresps (CD31+-memory-Tregs/Tresps), their direct proliferation via CD45RA+CD31−-mature naïve (MN)-Tregs/Tresps, and the production and differentiation of resting MN-Tregs/Tresp into CD45RA−CD31−-memory-Tregs/Tresps (CD31−-memory-Tregs/Tresps) were examined in 115 healthy controls, 96 SLE remission patients, and 20 active disease patients using six color flow cytometric analysis. In healthy controls an appropriate sequence of these pathways ensured regular age-dependent differentiation. In SLE patients, an age-independently exaggerated differentiation was observed for all Treg/Tresp subsets, where the increased conversion of resting MN-Tregs/Tresps particularly guaranteed the significantly increased ratios of ICOS+-Tregs/ICOS+-Tresps and ICOS−-Tregs/ICOS−-Tresps during remission. Changes in the differentiation of resting ICOS+-MN-Tresps and ICOS−-MN-Tregs from conversion to proliferation caused a significant shift in the ratio of ICOS+-Tregs/ICOS+-Tresps in favor of ICOS+-Tresps and a further increase in the ratio of ICOS−-Tregs/ICOS−-Tresps with active disease. The differentiation of ICOS+-RTE-Tregs/Tresps seems to be crucial for keeping patients in remission, where their limited production of proliferating resting MN-Tregs may be responsible for the occurrence of active disease flares.

CD80 (B7.1) Is Expressed On Both Malignant B Cells and Tumor Infiltrating T Cells in Non-Hodgkin's Lymphomas.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1953-1953
Author(s):  
Shabnam Tangri ◽  
Naveen Dakappagari ◽  
Annalee Estrellado ◽  
Andrew P. Weng ◽  
Elizabeth Holmes ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
Conflicts Of Interest ◽  
Cell Lymphoma ◽  
Flow Cytometric Analysis ◽  
B Cell Lymphoma ◽  
Low Grade ◽  
Malignant Cells ◽  
Color Flow ◽  
Hodgkin's Lymphomas

Abstract Abstract 1953 Poster Board I-976 CD80 is a member of the B7/CD28 family of regulatory proteins. B7/CD28 proteins are expressed on the surface of cells of the adaptive and innate immune system (i.e. lymphocytes, monocyte/macrophages, dendritic cells, myeloid-derived suppressor cells). These proteins function to establish a biologically optimal and dynamic balance between immune activation and inhibition or self-tolerance. Interactions between CD80 and its receptors, which include CD28, CTLA4 and PD-L1, contribute to both stimulatory as well as inhibitory or homeostatic regulation. Galiximab, an antibody directed against CD80, is currently under investigation for the treatment of follicular NHL. Initial clinical trials demonstrated that galiximab is well tolerated and suggest that combining galiximab with rituximab may provide clinical benefit. While expression of CD80 by malignant B cells in non-Hodgkin's lymphoma (NHL) has been reported, these studies utilized poorly quantitative immunohistochemical methods. To gain further understanding of the potential role of CD80 as a therapeutic target in NHL, CD80 expression was evaluated by six-color flow cytometric analysis of primary lymphoma cell suspensions generated from diagnostic biopsies of patients presenting with lymphadenopathy. Results obtained to date confirm that CD80 is uniformly expressed by malignant cells in a large majority of cases of follicular lymphoma (N=63), diffuse large B cell lymphoma (N=38), mantle cell lymphoma (n=7), marginal zone lymphoma (n=12) and small lymphocytic lymphoma (n=9). Furthermore, CD80 expression was also observed on tumor-infiltrating, non-malignant T cells. These results confirm the nearly ubiquitous expression of CD80 by malignant B cells in follicular, diffuse and other low grade NHL. Furthermore, these data demonstrate expression of CD80 by non-malignant cells (e.g. T cells) that define the tumor microenvironment. Further work to expand this dataset and to evaluate the expression of CD80 in non-T, non-B cells is ongoing. The expression of CD80 by malignant cells as well as non-malignant cells in NHL provides an opportunity to not only employ therapeutic antibodies to direct anti-tumor effector function such as antibody-dependent cellular cytotoxicity, but to also potentially interfere with interactions involving CD80 that might be involved in establishing an immune suppressive microenvironment supportive of tumor growth. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Perforin gene mutations in patients with acquired aplastic anemia

Blood ◽  
2007 ◽  
Vol 109 (12) ◽  
pp. 5234-5237 ◽  
Author(s):  
Elena E. Solomou ◽  
Federica Gibellini ◽  
Brian Stewart ◽  
Daniela Malide ◽  
Maria Berg ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Aplastic Anemia ◽  
Natural Killer ◽  
Nk Cell ◽  
Bone Marrow Failure ◽  
Genetic Alterations ◽  
Cytotoxic Lymphocytes ◽  
Activated T Cells ◽  
Hematopoietic Stem

Abstract Perforin is a cytolytic protein expressed mainly in activated cytotoxic lymphocytes and natural killer cells. Inherited perforin mutations account for 20% to 40% of familial hemophagocytic lymphohistiocytosis, a fatal disease of early childhood characterized by the absence of functional perforin. Aplastic anemia, the paradigm of immune-mediated bone marrow failure syndromes, is characterized by hematopoietic stem cell destruction by activated T cells and Th1 cytokines. We examined whether mutations in the perforin gene occurred in acquired aplastic anemia. Three nonsynonymous PRF1 mutations among 5 unrelated patients were observed. Four of 5 patients with the mutations showed some hemophagocytosis in the bone marrow at diagnosis. Perforin protein levels in these patients were very low or absent, and perforin granules were completely absent. Natural killer (NK) cell cytotoxicity from these patients was significantly decreased. Our data suggest that PRF1 genetic alterations help explain the aberrant proliferation and activation of cytotoxic T cells and may represent genetic risk factors for bone marrow failure.

scholarly journals A Novel P-Selectin Glycoprotein Ligand-1 Monoclonal Antibody Recognizes an Epitope Within the Tyrosine Sulfate Motif of Human PSGL-1 and Blocks Recognition of Both P- and L-Selectin

Blood ◽  
1998 ◽  
Vol 91 (1) ◽  
pp. 154-164 ◽  
Author(s):  
Karen R. Snapp ◽  
Han Ding ◽  
Kristin Atkins ◽  
Roger Warnke ◽  
Francis W. Luscinskas ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
T Cells ◽  
B Cells ◽  
Nk Cells ◽  
Flow Cytometric Analysis ◽  
Lymphoid Cells ◽  
B Cell Differentiation ◽  
Tyrosine Sulfation ◽  
Color Flow ◽  
Cos Cells

Interactions between P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1) mediate the earliest “rolling” of leukocytes on the lumenal surface of endothelial cells at sites of inflammation. Previously, PSGL-1 has been shown to be the primary mediator of interactions between neutrophils and P-selectin, but studies on the ability of PSGL-1 to mediate interactions between P-selectin and other subsets of leukocytes have yielded variable and conflicting results. A novel IgG monoclonal antibody (MoAb) to human PSGL-1 was generated, and the specificity of this MoAb was confirmed by both flow cytometric analysis and Western blotting of cells transfected with human PSGL-1. This newly developed MoAb, KPL1, inhibited interactions between P-selectin expressing COS cells and either HL60 cells, neutrophils, or lymphocytes. Furthermore, KPL1 completely inhibited interactions between P-selectin and either purified CD4 T cells or neutrophils in a flow assay under physiological conditions, but had no effect on interactions of T cells or neutrophils with E-selectin. In addition, KPL1 blocked interactions between lymphoid cells transfected with L-selectin and COS cells expressing PSGL-1. The KPL1 epitope was mapped to a site within a consensus tyrosine sulfation motif of PSGL-1, previously shown to be essential for interaction with P-selectin and now shown to be essential for interaction with L-selectin, and to be distinct from the epitope identified by the PL1 function blocking anti-PSGL-1 MoAb. Two-color flow cytometry of normal leukocytes showed that while natural killer (NK) cells (CD16+), monocytes, CD4 and CD8 T cells, and α/β and γ/δ T cells were uniformly positive for PSGL-1, B cells expressed low levels of the KPL1 epitope. This low level of KPL1 staining was also observed immunohistologically in germinal centers, which had no detectable KPL1 staining, whereas T-cell areas (interfollicular region) were positive for KPL1. Interestingly, plasma cells in situ and interleukin-6–dependent myeloma cell lines were KPL1+. Thus, PSGL-1 is expressed on essentially all blood neutrophils, NK cells, B cells, T cells, and monocytes. Variation in tyrosine sulfation during B-cell differentiation may affect the ability of B cells to interact with P- and L-selectin.

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

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3264-3264
Author(s):  
Hideyoshi Noji ◽  
Tsutomu Shichishima ◽  
Masatoshi Okamoto ◽  
Kazuhiko Ikeda ◽  
Akiko Nakamura ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Leukemia ◽  
De Novo ◽  
Past History ◽  
Bone Marrow Failure ◽  
Flow Cytometric Analysis ◽  
Leukemic Cells ◽  
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 the bone marrow failure syndromes, including aplastic anemia and myelodysplastic syndrome, which are considered as pre-leukemic states. In this study, to know some condition of pre-leukemic states in patients with de novo acute leukemia, we investigated the expression of CD59 in leukemic cells from 25 patients (female: male=8: 17; mean age, 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 10 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 mean 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 single (n=4) or multiple (n=6) PIG-A mutations in coding region were found in leukemic cells from 10 patients with CD59− leukemic cells and all of the clones with the PIG-A mutations were statistically minor. Then, various clinacal parameters, including peripheral blood, bone marrow blood, and laboratory findings and the results of chromosomal analyses were statistically compared between 2 groups of patients with (n=16) and without CD59− leukemic cells (n=9). The reticulocyte counts (mean ± standard deviation; 10.5 ± 13.0 x 104/μl) and proportions of bone marrow erythroblast (17.5 ± 13.9%) in patients with only CD59+ leukemic cells were significantly higher than those in patients with CD59− leukemic cells (2.5 ± 1.7 x 10 4/μl; p<0.05 and 5.6 ± 6.2%; p<0.01, respectively). The proportions of bone marrow blasts (69.3 ± 21.1%) in patients with CD59− leukemic cells were significantly higher than that those in patients with only CD59+ leukemic cells (45.5 ± 19.3%; p<0.02). In conclusion, our findings indicate that leukemic cells derived from PNH clones may be fairly common in de novo acute leukemia patients, suggesting that bone marrow failure as pre-leukemic states may have already occurred in localized bone marrow even in de novo acute leukemia.

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