Actionable perturbations of damage responses by TCL1/ATM and epigenetic lesions form the basis of T-PLL.

T-cell prolymphocytic leukemia (T-PLL) is a rare and poor-prognostic mature T-cell malignancy. Here we integrated large-scale profiling data of alterations in gene expression, allelic copy number (CN), and nucleotide sequences in 111 well-characterized patients. Besides prominent signatures of T-cell activation and prevalent clonal variants, we also identify novel hot-spots for CN variability, fusion molecules, alternative transcripts, and progression-associated dynamics. The overall lesional spectrum of T-PLL is mainly annotated to axes of DNA damage responses, T-cell receptor/cytokine signaling, and histone modulation. We formulate a multi-dimensional model of T-PLL pathogenesis centered around a unique combination of TCL1 overexpression with damaging ATM aberrations as initiating core lesions. The effects imposed by TCL1 cooperate with compromised ATM toward a leukemogenic phenotype of impaired DNA damage processing. Dysfunctional ATM appears inefficient in alleviating elevated redox burdens and telomere attrition and in evoking a p53-dependent apoptotic response to genotoxic insults. As non-genotoxic strategies, synergistic combinations of p53 reactivators and deacetylase inhibitors reinstate such cell death execution.

Chronic lymphocytic leukemia and regulatory B cells share IL-10 competence and immunosuppressive function.

Chronic lymphocytic leukemia (CLL) can be immunosuppressive in humans and mice, and CLL cells share multiple phenotypic markers with regulatory B cells that are competent to produce interleukin (IL)-10 (B10 cells). To identify functional links between CLL cells and regulatory B10 cells, the phenotypes and abilities of leukemia cells from 93 patients with overt CLL to express IL-10 were assessed. CD5(+) CLL cells purified from 90% of the patients were IL-10-competent and secreted IL-10 following appropriate ex vivo stimulation. Serum IL-10 levels were also significantly elevated in CLL patients. IL-10-competent cell frequencies were higher among CLLs with IgV(H) mutations, and correlated positively with TCL1 expression. In the TCL1-transgenic (TCL1-Tg) mouse model of CLL, IL-10-competent B cells with the cell surface phenotype of B10 cells expanded significantly with age, preceding the development of overt, CLL-like leukemia. Malignant CLL cells in TCL1-Tg mice also shared immunoregulatory functions with mouse and human B10 cells. Serum IL-10 levels varied in TCL1-Tg mice, but in vivo low-dose lipopolysaccharide treatment induced IL-10 expression in CLL cells and high levels of serum IL-10. Thus, malignant IL-10-competent CLL cells exhibit regulatory functions comparable to normal B10 cells that may contribute to the immunosuppression observed in patients and TCL1-Tg mice.

Immunophenotypic and gene expression analysis of monoclonal B-cell lymphocytosis shows biologic characteristics associated with good prognosis CLL.

Monoclonal B-cell lymphocytosis (MBL) is a hematologic condition wherein small B-cell clones can be detected in the blood of asymptomatic individuals. Most MBL have an immunophenotype similar to chronic lymphocytic leukemia (CLL), and 'CLL-like' MBL is a precursor to CLL. We used flow cytometry to identify MBL from unaffected members of CLL kindreds. We identified 101 MBL cases from 622 study subjects; of these, 82 individuals with MBL were further characterized. In all, 91 unique MBL clones were detected: 73 CLL-like MBL (CD5(+)CD20(dim)sIg(dim)), 11 atypical MBL (CD5(+)CD20(+)sIg(+)) and 7 CD5(neg) MBL (CD5(neg)CD20(+)sIg(neg)). Extended immunophenotypic characterization of these MBL subtypes was performed, and significant differences in cell surface expression of CD23, CD49d, CD79b and FMC-7 were observed among the groups. Markers of risk in CLL such as CD38, ZAP70 and CD49d were infrequently expressed in CLL-like MBL, but were expressed in the majority of atypical MBL. Interphase cytogenetics was performed in 35 MBL cases, and del 13q14 was most common (22/30 CLL-like MBL cases). Gene expression analysis using oligonucleotide arrays was performed on seven CLL-like MBL, and showed activation of B-cell receptor associated pathways. Our findings underscore the diversity of MBL subtypes and further clarify the relationship between MBL and other lymphoproliferative disorders.

LMP-420: a novel purine nucleoside analog with potent cytotoxic effects for CLL cells and minimal toxicity for normal hematopoietic cells.

B-cell chronic lymphocytic leukemia (CLL) is characterized by slow accumulation of malignant cells, which are supported in the microenvironment by cell-cell interactions and soluble cytokines such as tumor necrosis factor (TNF). We evaluated the effect of the small molecule TNF inhibitor LMP-420 on primary CLL cells. The mean concentration of LMP-420 required to induce 50% cytotoxicity (ED50) at 72 h was 245 n. LMP-420-induced time- and dose-dependent apoptosis, as shown by annexin V staining, caspase activation and DNA fragmentation. These changes were associated with decreased expression of anti-apoptotic proteins Mcl-1, Bcl-xL and Bcl-2. CLL cells from patients with poor prognostic indicators showed LMP-420 sensitivity equal to that for cells from patients with favorable characteristics. In addition, LMP-420 potentiated the cytotoxic effect of fludarabine and inhibited in vitro proliferation of stimulated CLL cells. Gene expression profiling indicated that the mechanism of action of LMP-420 may involve suppression of nuclear factor-kappaB and immune response pathways in CLL cells. LMP-420 had minimal effects on normal peripheral blood mononuclear cell, B- and T-cell function, and hematopoietic colony formation. Our data suggest that LMP-420 may be a useful treatment for CLL with negligible hematologic toxicities.

Monoclonal B-cell lymphocytosis (MBL): biology, natural history and clinical management.

Chronic lymphocytic leukemia (CLL) and the other low-grade non-Hodgkin lymphomas are among the most common lymphoid malignancies. Recent studies suggest that more than 4% of the general population over age 40 harbor a population of clonal B cells with the phenotype of either CLL or another B-cell malignancy, a condition now designated monoclonal B-cell lymphocytosis (MBL). Although all cases of CLL appear to be preceded by MBL, the majority of individuals with MBL will not develop a hematologic malignancy. The biologic characteristics and clinical implications of MBL appear to differ based on whether it is identified during the diagnostic evaluation of lymphocytosis or incidentally discovered through screening of individuals with normal lymphocyte counts as part of research studies using highly sensitive detection methods. In this paper, we provide a state of the art review on the prevalence, nomenclature, biology, natural history and clinical management of MBL.

Single-cell analysis reveals oligoclonality among 'low-count' monoclonal B-cell lymphocytosis.

Monoclonal B-cell lymphocytosis (MBL) is a preclinical hematologic syndrome characterized by small accumulations of CD5(+) B lymphocytes. Most MBL share phenotypic characteristics with chronic lymphocytic leukemia (CLL). Although some MBL progress to CLL, most MBL have apparently limited potential for progression to CLL, particularly those MBL with normal absolute B-cell counts ('low-count' MBL). Most CLL are monoclonal and it is not known whether MBL are monoclonal or oligoclonal; this is important because it is unclear whether MBL represent indolent CLL or represent a distinct premalignant precursor before the development of CLL. We used flow cytometry analysis and sorting to determine immunophenotypic characteristics, clonality and molecular features of MBL from familial CLL kindreds. Single-cell analysis indicated four of six low-count MBL consisted of two or more unrelated clones; the other two MBL were monoclonal. 87% of low-count MBL clones had mutated immunoglobulin genes, and no immunoglobulin heavy-chain rearrangements of V(H) family 1 were observed. Some MBL were diversified, clonally related populations with evidence of antigen drive. We conclude that although low-count MBL share many phenotypic characteristics with CLL, many MBL are oligoclonal. This supports a model for step-wise development of MBL into CLL.

A novel X chromosome-linked genetic cause of recurrent spontaneous abortion.

OBJECTIVE: Unexplained recurrent spontaneous abortion is a common women's health problem that affects approximately 1 of every 200 women who wish to have children. It has long been assumed that a large proportion of recurrent spontaneous abortion results from genetic problems, but no causative genes have been identified to date. Here, we tested the hypothesis that a subset of women with recurrent spontaneous abortion are carriers of X-linked recessive disorders that result in the loss of male pregnancies. STUDY DESIGN: X chromosome inactivation patterns, an assay used to detect women who are likely to be carriers of X-linked recessive cell-lethal traits, were compared between 105 female patients with idiopathic recurrent pregnancy loss and 101 women (control subjects) with a single successful pregnancy and no history of pregnancy loss. Inheritance patterns and gender of offspring were studied in relevant subsets of participants. RESULTS: Female patients showed a highly statistically significant increase in the frequency of skewed X chromosome inactivation (90%; P < .0005). Female patients with highly skewed X chromosome inactivation showed a significant decrease in male children. Four of 6 families that were studied showed maternal inheritance of the skewed inactivation trait. CONCLUSION: We found the 14% of women with unexplained recurrent pregnancy loss show highly skewed X inactivation, which suggests that they are carriers of X-linked recessive lethal traits. Furthermore, the observed gender bias among women with highly skewed X inactivation suggests selective loss of male conceptions, which is consistent with an X chromosome-linked genetic defect that leads to cell death or growth disadvantage. Identification of such female carriers is important for the reproductive counseling and treatment of these women.

X chromosome defects as an etiology of recurrent spontaneous abortion.

Recurrent spontaneous abortion is a significant problem in women's health, yet it remains a poorly understood phenomenon. Many cases of recurrent spontaneous abortion defy diagnosis, and we predict that a subset of these unexplained cases are caused by previously unknown, recessively inherited genetic causes. Here, we provide background on known genetic factors that contribute to spontaneous abortion and describe a novel X chromosome-based genetic mechanism that may be an important cause of recurrent spontaneous abortion. Recessively inherited defects on the human X chromosome would cause no symptoms in carrier females but would be lethal in utero to male conceptions that receive the defective X. Through investigation of the basic biology of the X chromosome, we propose that the female carriers of such traits can be identified through the molecular finding of skewed X chromosome inactivation. Furthermore, we have observed an association between skewed X chromosome inactivation and recurrent pregnancy loss, supporting the hypothesis that X chromosome defects may be an important, previously unknown cause of recurrent pregnancy loss.

Familial skewed X inactivation: a molecular trait associated with high spontaneous-abortion rate maps to Xq28.

We report a family ascertained for molecular diagnosis of muscular dystrophy in a young girl, in which preferential activation (> or = 95% of cells) of the paternal X chromosome was seen in both the proband and her mother. To determine the molecular basis for skewed X inactivation, we studied X-inactivation patterns in peripheral blood and/or oral mucosal cells from 50 members of this family and from a cohort of normal females. We found excellent concordance between X-inactivation patterns in blood and oral mucosal cell nuclei in all females. Of the 50 female pedigree members studied, 16 showed preferential use (> or = 95% cells) of the paternal X chromosome; none of 62 randomly selected females showed similarly skewed X inactivation was maternally inherited in this family. A linkage study using the molecular trait of skewed X inactivation as the scored phenotype localized this trait to Xq28 (DXS1108; maximum LOD score [Zmax] = 4.34, recombination fraction [theta] = 0). Both genotyping of additional markers and FISH of a YAC probe in Xq28 showed a deletion spanning from intron 22 of the factor VIII gene to DXS115-3. This deletion completely cosegregated with the trait (Zmax = 6.92, theta = 0). Comparison of clinical findings between affected and unaffected females in the 50-member pedigree showed a statistically significant increase in spontaneous-abortion rate in the females carrying the trait (P < .02). To our knowledge, this is the first gene-mapping study of abnormalities of X-inactivation patterns and is the first association of a specific locus for recurrent spontaneous abortion in a cytogenetically normal family. The involvement of this locus in cell lethality, cell-growth disadvantage, developmental abnormalities, or the X-inactivation process is discussed.