Loss-of-function mutations affecting one or both copies of the Ten-Eleven-translocation (TET)2 gene have been described in various human myeloid malignancies. We report that inactivation of Tet2 in mouse perturbs both early and late steps of hematopoiesis including myeloid and lymphoid differentiation in a cell-autonomous manner, endows the cells with competitive advantage, and eventually leads to the development of malignancies. We subsequently observed TET2 mutations in human lymphoid disorders. TET2 mutations could be detected in immature progenitors endowed with myeloid colony-forming potential. Our results show that the mutations present in lymphoid tumor cells may occur at both early and later steps of lymphoid development and indicate that impairment of TET2 function or/and expression predisposes to the development of hematological malignancies.

Mounting evidence indicates that grouping of chronic lymphocytic leukemia (CLL) into distinct subsets with stereotypedBCRs is functionally and prognostically relevant. However, several issues need revisiting, including the criteria for identification of BCR stereotypy and its actual frequency as well as the identification of "CLL-biased" features in BCR Ig stereotypes. To this end, we examined 7596 Ig VH (IGHV-IGHD-IGHJ) sequences from 7424 CLL patients, 3 times the size of the largest published series, with an updated version of our purpose-built clustering algorithm. We document that CLL may be subdivided into 2 distinct categories: one with stereotyped and the other with nonstereotyped BCRs, at an approximate ratio of 1:2, and provide evidence suggesting a different ontogeny for these 2 categories. We also show that subset-defining sequence patterns in CLL differ from those underlying BCR stereotypy in other B-cell malignancies. Notably, 19 major subsets contained from 20 to 213 sequences each, collectively accounting for 943 sequences or one-eighth of the cohort. Hence, this compartmentalized examination of VH sequences may pave the way toward a molecular classification of CLL with implications for targeted therapeutic interventions, applicable to a significant number of patients assigned to the same subset. (Blood. 2012;119(19):4467-4475) IntroductionThe analysis of the Ig genes in chronic lymphocytic leukemia (CLL) has contributed significantly toward deciphering the molecular pathogenesis of the disease. Studies from the 1990s provided the first indications for a possible role of Ag(s) in selecting the CLL progenitor cells, through the discovery of a biased Ig heavy variable (IGHV) gene repertoire, different from that of normal B cells, as well as distinctive Ag-binding sites among unrelated cases. [1][2][3][4][5] By the late 1990s, it emerged that the mutational status of the rearranged IGHV genes directly correlated with patient survival. In particular, patients with unmutated IGHV genes were found to follow a more aggressive clinical course and have significantly shorter survival than patients carrying mutated IGHV genes. 6,7 Yet, there were exceptions to this rule: cases using the IGHV3-21 gene, although mostly expressing mutated Ig, had a survival similar to that of unmutated cases. 8 Intriguingly, approximately half of the IGHV3-21 cases were found to display restricted and, in some instances, essentially identical variable heavy complementarity determining region 3 (VH CDR3) sequences and identical light chains, strongly suggesting recognition of a common antigenic determinant. 9 Soon thereafter, the study of Ig sequences in CLL by groups in both Europe and the United States led to the identification of several other subsets of cases carrying highly similar BCR Igs among both mutated and unmutated cases (stereotyped BCR). [10][11][12][13][14] The identification of stereotypy among unrelated and geographically distant cases was widely accepted as evidence for the Submitted November 26, 2011; accepte...

Due to a production error, Table 1 was inadvertently left out of the article as it was originally published. The table is printed below and the online article has been corrected. We apologize for any confusion that may have occurred.

Chronic lymphocytic leukemia (CLL) immunoglobulin repertoire is biased. Furthermore, subsets of closely homologous (“stereotyped”) complementarity-determining region 3 (CDR3) sequences were recently described in CLL patients. In the present study, we evaluated the frequency and characteristics of these homologous subsets in a cohort of 916 CLL patients. We report that 201 cases (21.9%) expressed IGHV genes which belonged to one of 48 different subsets of sequences with stereotyped heavy chain (H) CDR3, of which only ten have been reported previously. Within each stereotyped HCDR3 subset, the IG sequences might show the usage of identical or different IGHV genes. In the latter case, the IGHV genes most often belonged to the same IGHV subgroup or clan or carried homologous HCDR1. Each subset included up to 20 cases. A similar proportion of HCDR3 restriction (80/462 cases; 17.3%) was found among public-database CLL sequences; comparison to 6430 non-CLL public database IGHV-D-J sequences showed that this is a “CLL-related” feature. In our series, the chance of belonging to a subset was even (p<0.001) higher for unmutated IGHV sequences (35%); furthermore, it exceeded 30% in cases using selected IGHV genes (e.g., IGHV3-21/1-69/1-2/1-3/4-39/3-48). Database and literature searches revealed that 64/916 CLL cases belonging to seven different subsets displayed HCDR3 homology with various autoantibodies, including rheumatoid factors and anti-cardiolipin antibodies. In our series, CLL cases with selected stereotyped IGs were also found to share unique biological and clinical features. In particular, cases expressing stereotyped IGHV4-34/IGKV2-30 B cell receptors (BCRs) were of significantly younger age and followed a strikingly indolent disease, whereas those expressing, IGHV3-21/IGLV3-21 BCRs experienced an aggressive disease, regardless of IGHV mutation status. Furthermore, among patients expressing unmutated IGHV1-69 genes, we identified a subset (IGHV1-69/IGHD3-10/IGHJ6) with higher overall survival (OS) compared to another subset (IGHV1-69/IGHD2-2/IGHJ6) with significantly shorter OS (log Rank test=0.05). In conclusion, the unique, “CLL-biased” molecular features of stereotyped HCDR3 sequences suggest a role for antigen not only in driving the cell of origin but also in determining the clinical features and outcome for at least some CLL patients. Considering the clinical-biological associations with certain subsets, it is conceivable that future therapeutic decisions should be based not only on mutational status of IGHV genes but also on individual HCDR3 characteristics.

SummaryAging is generally associated with an increased predisposition to infectious diseases and cancers, related in part to the development of immune senescence, a process that affects all cell compartments of the immune system. Although many studies have investigated the effects of age on natural killer (NK) cells, their conclusions remain controversial because the diverse health status of study subjects resulted in discordant findings. To clarify this situation, we conducted the first extensive phenotypic and functional analysis of NK cells from healthy subjects, comparing NK cells derived from newborn (cord blood), middle-aged (18-60 years), old (60-80 years), and very old (80-100 years) subjects. We found that NK cells in cord blood displayed specific features associated with immaturity, including poor expression of KIR and LIR-1 ⁄ ILT-2 and high expression of both NKG2A and IFN-c. NK cells from older subjects, on the other hand, preserved their major phenotypic and functional characteristics, but with their mature features accentuated. These include a profound decline of the CD56 bright subset, a specific increase in LIR-1 ⁄ ILT-2, and a perfect recovering of NK-cell function following IL2-activation in very old subjects. We conclude that the preservation of NK cell features until very advanced age may contribute to longevity and successful aging.

The prognosis of the disease remains poor. However, the new diagnostic tools and therapeutic strategies may improve the diagnostic delay and the survival outcome.

Although the zeta-associated protein of 70 kDa (ZAP-70) is overexpressed in patients with chronic lymphocytic leukemia (CLL) displaying unmutated IGVH genes and poor prognosis, a previous microarray study from our group identified overexpression of LPL and ADAM29 genes among unmutated and mutated CLL, respectively. To assess the prognostic value of these genes, we quantified their expression by real-time quantitative polymerase chain reaction (

In this study, we explored the telomeric changes that occur in B-chronic lymphocytic leukemia (B-CLL), in which telomere length has recently been demonstrated to be a powerful prognostic marker. We carried out a transcriptomic analysis of telomerase components (hTERT and DYSKERIN), shelterin proteins (TRF1, TRF2, hRAP1, TIN2, POT1, and TPP1), and a set of multifunctional proteins involved in telomere maintenance (hEST1A, MRE11, RAD50, Ku80, and RPA1) in peripheral B cells from 42 B-CLL patients and 20 healthy donors. We found that, in B-CLL cells, the expressions of hTERT, DYSKERIN, TRF1, hRAP1, POT1, hEST1A, MRE11, RAD50, and KU80 were more than 2-fold reduced (P < .001), contrasting with the higher expression of IntroductionTelomeres are nucleoprotein structures that cap chromosomes and shorten with each division. Telomere structure and functions depend on the telomerase enzyme (hTERT, hTR, DYSKERIN) for elongation, 1 on the shelterin complex (TRF1, TRF2, TIN2, hRAP1, TPP1, POT1) that regulates telomere length and protects them against degradation and fusion, and on a set of multifunctional factors, including RPA1, hEST1A, KU70/KU80 and the RAD50-MRE11-NBS1 complex 2 ( Figure 1A).Telomerase activity is absent or very low in somatic cells and increased in proliferative lymphoid cells. 3 In most cancer cells, the catalytic subunit of telomerase (hTERT) is overexpressed to allow their long-term proliferation. 4 Research in oncogenesis is now focusing on the other telomeric genes, especially the shelterin complex. [5][6][7][8][9][10] Specific changes in the expression of these genes in cancers may provide new knowledge about oncogenesis and useful clinical markers, but would also lead to the development of new therapeutic agents.B-cell chronic lymphocytic leukemia (B-CLL) results from the progressive accumulation of a leukemic clone (for review, see Chiorazzi and Ferrarini 11 ) that shows lower telomerase activity at disease onset 12 and increased activity in advanced stages and bad prognosis group. 13 Telomeres are shorter in B-CLL cells versus normal B cells, and especially short for patients with bad prognosis. Telomere length is thus a powerful prognostic marker for B-CLL. 13,14 In this work, we investigated whether the transcriptional status of the telomeric proteins is modified in B cells from B-CLL patients. Methods Isolation of human B cellsAfter consent was obtained in accordance with the Declaration of Helsinki and according to institutional guidelines, total blood samples were collected from 20 healthy donors (at the "Etablissement Français du Sang" of Lyon and Pitié-Salpétrière Hospital) and from 42 B-CLL patients (at the Lyon Sud and Pitié-Salpétrière Hospitals). Diagnoses were confirmed using morphology and flow-cytometry usual B-CLL characteristics (Matutes score Ն 4). B lymphocytes were purified from peripheral blood by negative selection using the RosetteSep Human B-cell enrichment cocktail (Stem Cell Technologies, Vancouver, BC). The percentage of CD19 ϩ cells was determined by cytometric assay ...