scholarly journals The proto-oncogene c-fgr is expressed in normal mantle zone B lymphocytes and is developmentally regulated during myelomonocytic differentiation in vivo

Blood ◽  
1995 ◽  
Vol 85 (2) ◽  
pp. 472-479
Author(s):  
DC Link ◽  
M Zutter
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Lymphocytes ◽  
B Lymphocyte ◽  
Lymphocyte Subpopulation ◽  
Lymphoproliferative Disorders ◽  
Lymphocytic Leukemia ◽  
Lymphoid Tissues ◽  
Mantle Zone ◽  
Developmentally Regulated

The proto-oncogene c-fgr is a member of the c-src gene family of cytoplasmic tyrosine kinases. Previous studies have suggested that it is normally expressed in neutrophils, monocytes, macrophages, and natural killer cells. c-fgr is also expressed in the B cells of certain lymphoproliferative disorders, namely, Epstein-Barr virus-associated lymphoproliferative disease, and in chronic lymphocytic leukemia, but it has not previously been detected in normal or reactive human lymphoid tissue. In this study we have determined the pattern of p55c- fgr protein expression in normal human hematopoietic and lymphoid tissues at the single-cell level using immunohistochemical and immunofluorescent techniques. We show that p55c-fgr expression is developmentally regulated with high-level expression first evident at the myelocyte stage of myeloid differentiation. In addition, we show that p55c-fgr is expressed in circulating B lymphocytes isolated from chronic lymphocytic leukemia patients but is not expressed in normal circulating B lymphocytes. Surprisingly, p55c-fgr is also expressed in a subpopulation of normal B lymphocytes, the mantle zone B lymphocytes. This demonstration that p55c-fgr is expressed in a normal B-lymphocyte subpopulation suggests that its expression in certain B-cell lymphoproliferative disorders may be an indirect consequence of, rather than a primary cause of, the neoplastic transformation process.

scholarly journals The proto-oncogene c-fgr is expressed in normal mantle zone B lymphocytes and is developmentally regulated during myelomonocytic differentiation in vivo

Blood ◽  
1995 ◽  
Vol 85 (2) ◽  
pp. 472-479 ◽  
Author(s):  
DC Link ◽  
M Zutter
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Lymphocytes ◽  
B Lymphocyte ◽  
Lymphocyte Subpopulation ◽  
Lymphoproliferative Disorders ◽  
Lymphocytic Leukemia ◽  
Lymphoid Tissues ◽  
Mantle Zone ◽  
Developmentally Regulated

Abstract The proto-oncogene c-fgr is a member of the c-src gene family of cytoplasmic tyrosine kinases. Previous studies have suggested that it is normally expressed in neutrophils, monocytes, macrophages, and natural killer cells. c-fgr is also expressed in the B cells of certain lymphoproliferative disorders, namely, Epstein-Barr virus-associated lymphoproliferative disease, and in chronic lymphocytic leukemia, but it has not previously been detected in normal or reactive human lymphoid tissue. In this study we have determined the pattern of p55c- fgr protein expression in normal human hematopoietic and lymphoid tissues at the single-cell level using immunohistochemical and immunofluorescent techniques. We show that p55c-fgr expression is developmentally regulated with high-level expression first evident at the myelocyte stage of myeloid differentiation. In addition, we show that p55c-fgr is expressed in circulating B lymphocytes isolated from chronic lymphocytic leukemia patients but is not expressed in normal circulating B lymphocytes. Surprisingly, p55c-fgr is also expressed in a subpopulation of normal B lymphocytes, the mantle zone B lymphocytes. This demonstration that p55c-fgr is expressed in a normal B-lymphocyte subpopulation suggests that its expression in certain B-cell lymphoproliferative disorders may be an indirect consequence of, rather than a primary cause of, the neoplastic transformation process.

scholarly journals A novel adoptive transfer model of chronic lymphocytic leukemia suggests a key role for T lymphocytes in the disease

Blood ◽  
2011 ◽  
Vol 117 (20) ◽  
pp. 5463-5472 ◽  
Author(s):  
Davide Bagnara ◽  
Matthew S. Kaufman ◽  
Carlo Calissano ◽  
Sonia Marsilio ◽  
Piers E. M. Patten ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
T Lymphocytes ◽  
Adoptive Transfer ◽  
Severe Combined Immunodeficiency ◽  
Immune Surveillance ◽  
Lymphocytic Leukemia ◽  
Unknown Etiology ◽  
Lymphoid Tissues ◽  
Transfer Model

AbstractChronic lymphocytic leukemia (CLL) is an incurable adult disease of unknown etiology. Understanding the biology of CLL cells, particularly cell maturation and growth in vivo, has been impeded by lack of a reproducible adoptive transfer model. We report a simple, reproducible system in which primary CLL cells proliferate in nonobese diabetes/severe combined immunodeficiency/γcnull mice under the influence of activated CLL-derived T lymphocytes. By cotransferring autologous T lymphocytes, activated in vivo by alloantigens, the survival and growth of primary CFSE-labeled CLL cells in vivo is achieved and quantified. Using this approach, we have identified key roles for CD4+ T cells in CLL expansion, a direct link between CD38 expression by leukemic B cells and their activation, and support for CLL cells preferentially proliferating in secondary lymphoid tissues. The model should simplify analyzing kinetics of CLL cells in vivo, deciphering involvement of nonleukemic elements and nongenetic factors promoting CLL cell growth, identifying and characterizing potential leukemic stem cells, and permitting preclinical studies of novel therapeutics. Because autologous activated T lymphocytes are 2-edged swords, generating unwanted graph-versus-host and possibly autologous antitumor reactions, the model may also facilitate analyses of T-cell populations involved in immune surveillance relevant to hematopoietic transplantation and tumor cytoxicity.

scholarly journals Chronic Lymphocytic Leukemia B Cells Can Undergo Somatic Hypermutation and Intraclonal Immunoglobulin VHDJH Gene Diversification

2002 ◽  
Vol 196 (5) ◽  
pp. 629-639 ◽  
Author(s):  
Carmela Gurrieri ◽  
Peter McGuire ◽  
Hong Zan ◽  
Xiao-Jie Yan ◽  
Andrea Cerutti ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Lymphocyte ◽  
Somatic Hypermutation ◽  
Point Mutations ◽  
Single Strand Conformation Polymorphism ◽  
Lymphocytic Leukemia ◽  
Gene Diversification

Chronic lymphocytic leukemia (CLL) arises from the clonal expansion of a CD5+ B lymphocyte that is thought not to undergo intraclonal diversification. Using VHDJH cDNA single strand conformation polymorphism analyses, we detected intraclonal mobility variants in 11 of 18 CLL cases. cDNA sequence analyses indicated that these variants represented unique point-mutations (1–35/patient). In nine cases, these mutations were unique to individual submembers of the CLL clone, although in two cases they occurred in a large percentage of the clonal submembers and genealogical trees could be identified. The diversification process responsible for these changes led to single nucleotide changes that favored transitions over transversions, but did not target A nucleotides and did not have the replacement/silent nucleotide change characteristics of antigen-selected B cells. Intraclonal diversification did not correlate with the original mutational load of an individual CLL case in that diversification was as frequent in CLL cells with little or no somatic mutations as in those with considerable mutations. Finally, CLL B cells that did not exhibit intraclonal diversification in vivo could be induced to mutate their VHDJH genes in vitro after stimulation. These data indicate that a somatic mutation mechanism remains functional in CLL cells and could play a role in the evolution of the clone.

Chronic Lymphocytic Leukemia-Exosomes Switch Endothelial and Mesenchymal Stromal Cells into Cancer-Associated Fibroblasts to Sustain Leukemic Cell Survival

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2927-2927 ◽  
Author(s):  
Jerome Paggetti ◽  
Franziska Haderk ◽  
Martina Seiffert ◽  
Bassam Janji ◽  
Yeoun Jin Kim ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Chronic Lymphocytic Leukemia ◽  
Cell Survival ◽  
B Lymphocytes ◽  
Stromal Cells ◽  
Leukemic Cell ◽  
Lymphoid Organs ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells

Abstract Chronic lymphocytic leukemia (CLL), the most common hematologic malignancy in Western countries, is mostly affecting the elderly over 65 year-old. CLL is characterized by the accumulation of mature but non-functional B lymphocytes of clonal origin in the blood and the primary lymphoid organs. CLL was previously considered as a relatively static disease resulting from the accumulation of apoptosis-resistant but quiescent B lymphocytes. However, recent studies using heavy water labeling indicated that CLL is in fact a very dynamic disease with alternation of proliferation phases and peripheral circulation. A focus on the trafficking of CLL cells in vivo has shown that leukemic cells circulate between the blood and the lymphoid organs but have a preference for the bone marrow. Recent next-generation sequencing of CLL cells indicated the presence of different genetic subclones. This intraclonal heterogeneity observed in CLL subpopulations may be in part determined by the interactions that leukemic cells entertain with their microenvironment when B cells migrate into the lymph nodes and the bone marrow. Indeed, tumor-stroma interactions are not only providing signals necessary for leukemic cells survival but may also influence the clonal architecture and evolution. One of these interactions involves CLL-derived exosomes. Here, we show that CLL-exosomes efficiently transfer nucleic acids, including functional microRNAs, and proteins, including MHC-Class II molecules and B-cell specific proteins, to bone marrow mesenchymal stem cells and endothelial cells. CLL-exosomes also activate signaling pathways, including PI3K and NF-κB pathways, in these stromal cells. As a consequence, gene expression is strongly modified indicating a switch towards a cancer-associated fibroblast phenotype. Functionally, exosome-stimulated stromal cells show a striking actin cytoskeleton remodeling characterized by the formation of stress fibers, and enhanced proliferation, motility and angiogenic properties. We also identified several proteins synthesized and secreted by stromal cells that promote leukemic cell adhesion and survival ex vivo. To confirm the involvement of CLL-exosomes in CLL pathology in vivo, MEC-1-eGFP cells were subcutaneously injected into immunocompromised NSG mice together with CLL-exosomes. We observed a significant increase in tumor size and a reduction in survival of exosome-treated animals. Flow cytometry analysis of selected organs indicated an enrichment in leukemic cells in the kidney, providing a potential explanation to the renal failures observed in CLL patients. In conclusion, the communication between CLL cells and stromal cells may be a critical factor influencing CLL progression by promoting leukemic cell survival. This study demonstrates the crucial role of exosomes as mediators of the communication between leukemic cells and their microenvironment. Exosomes could thus represent a suitable target for therapeutic intervention in CLL. Disclosures No relevant conflicts of interest to declare.

scholarly journals Production of autoantibodies by CD5-expressing B lymphocytes from patients with chronic lymphocytic leukemia.

1989 ◽  
Vol 169 (1) ◽  
pp. 255-268 ◽  
Author(s):  
Z M Sthoeger ◽  
M Wakai ◽  
D B Tse ◽  
V P Vinciguerra ◽  
S L Allen ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Lymphocytes ◽  
Autoimmune Disorders ◽  
Lymphoproliferative Disorders ◽  
Lymphocytic Leukemia ◽  
Antigenic Specificity ◽  
Human B Cells ◽  
Well Differentiated

CD5-expressing B lymphocytes from patients with selected chronic lymphoproliferative disorders were used to determine whether monoclonal populations of CD5+ human B cells produce autoantibodies. CD5+ B cells from 19 patients with chronic lymphocytic leukemia (CLL) and one with diffuse well-differentiated lymphocytic lymphoma (DWDL) were cultured, with and without mitogenic stimulation, to obtain Ig from these cells. 17 of the 20 samples produced Ig in vitro. mAb from nine of the 17 patients were reactive with either IgG, ssDNA, or dsDNA. In every instance, the autoantibodies displayed monotypic L chain usage that correlated precisely with the L chain expressed on the CD5+ leukemic B cell surface. These monoclonal autoantibodies varied in their degree of antigenic specificity; some were quite specific, reacting with only one antigen, whereas others were polyspecific, reacting with two or all three autoantigens tested. Three features distinguish these autoantibodies from those observed in prior studies of CD5+ B cells. First, they are clearly the products of monoclonal populations of CD5+ cells; second, several react with dsDNA, a specificity not previously reported and often seen in association with significant autoimmune disorders; and third, two of the monoclonal autoantibodies secreted by the CD5+ clones were of the IgG class. Although not all of the Ig-producing, CD5-expressing clones elaborated mAbs reactive with the autoantigens tested, greater than 50% did. It is possible that with a broader autoantigenic panel or with larger quantities of CLL/DWDL-derived Ig, even more autoantibody-producing clones might be identified. These studies may have important implications for the antigenic specificity of subsets of human B lymphocytes as well as for lymphoproliferative and autoimmune disorders in general.

scholarly journals A Detailed Analysis of Parameters Supporting the Engraftment and Growth of Chronic Lymphocytic Leukemia Cells in Immune-Deficient Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Piers E. M. Patten ◽  
Gerardo Ferrer ◽  
Shih-Shih Chen ◽  
Jonathan E. Kolitz ◽  
Kanti R. Rai ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Intraperitoneal Administration ◽  
Human Condition ◽  
Lymphocytic Leukemia ◽  
Lymphoid Tissues ◽  
Quiescent State

Patient-derived xenograft models of chronic lymphocytic leukemia (CLL) can be created using highly immunodeficient animals, allowing analysis of primary tumor cells in an in vivo setting. However, unlike many other tumors, CLL B lymphocytes do not reproducibly grow in xenografts without manipulation, proliferating only when there is concomitant expansion of T cells. Here we show that in vitro pre-activation of CLL-derived T lymphocytes allows for a reliable and robust system for primary CLL cell growth within a fully autologous system that uses small numbers of cells and does not require pre-conditioning. In this system, growth of normal T and leukemic B cells follows four distinct temporal phases, each with characteristic blood and tissue findings. Phase 1 constitutes a period during which resting CLL B cells predominate, with cells aggregating at perivascular areas most often in the spleen. In Phase 2, T cells expand and provide T-cell help to promote B-cell division and expansion. Growth of CLL B and T cells persists in Phase 3, although some leukemic B cells undergo differentiation to more mature B-lineage cells (plasmablasts and plasma cells). By Phase 4, CLL B cells are for the most part lost with only T cells remaining. The required B-T cell interactions are not dependent on other human hematopoietic cells nor on murine macrophages or follicular dendritic cells, which appear to be relatively excluded from the perivascular lymphoid aggregates. Notably, the growth kinetics and degree of anatomic localization of CLL B and T cells is significantly influenced by intravenous versus intraperitoneal administration. Importantly, B cells delivered intraperitoneally either remain within the peritoneal cavity in a quiescent state, despite the presence of dividing T cells, or migrate to lymphoid tissues where they actively divide; this dichotomy mimics the human condition in that cells in primary lymphoid tissues and the blood are predominately resting, whereas those in secondary lymphoid tissues proliferate. Finally, the utility of this approach is illustrated by documenting the effects of a bispecific antibody reactive with B and T cells. Collectively, this model represents a powerful tool to evaluate CLL biology and novel therapeutics in vivo.

scholarly journals In vitro and in vivo model of a novel immunotherapy approach for chronic lymphocytic leukemia by anti-CD23 chimeric antigen receptor

Blood ◽  
2011 ◽  
Vol 117 (18) ◽  
pp. 4736-4745 ◽  
Author(s):  
Greta Maria Paola Giordano Attianese ◽  
Virna Marin ◽  
Valentina Hoyos ◽  
Barbara Savoldo ◽  
Irene Pizzitola ◽  
...  
Keyword(s):  
T Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Lymphocytes ◽  
Chimeric Antigen Receptor ◽  
Antigen Receptor ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Car T Cells ◽  
Car T

Abstract Chronic lymphocytic leukemia (CLL) is characterized by an accumulation of mature CD19+CD5+CD20dim B lymphocytes that typically express the B-cell activation marker CD23. In the present study, we cloned and expressed in T lymphocytes a novel chimeric antigen receptor (CAR) targeting the CD23 antigen (CD23.CAR). CD23.CAR+ T cells showed specific cytotoxic activity against CD23+ tumor cell lines (average lysis 42%) and primary CD23+ CLL cells (average lysis 58%). This effect was obtained without significant toxicity against normal B lymphocytes, in contrast to CARs targeting CD19 or CD20 antigens, which are also expressed physiologically by normal B lymphocytes. Moreover, CLL-derived CD23.CAR+ T cells released inflammatory cytokines (1445-fold more TNF-β, 20-fold more TNF-α, and 4-fold more IFN-γ). IL-2 was also produced (average release 2681 pg/mL) and sustained the antigen-dependent proliferation of CD23.CAR+ T cells. Redirected T cells were also effective in vivo in a CLL Rag2−/−γc−/− xenograft mouse model. Compared with mice treated with control T cells, the infusion of CD23.CAR+ T cells resulted in a significant delay in the growth of the MEC-1 CLL cell line. These data suggest that CD23.CAR+ T cells represent a selective immunotherapy for the elimination of CD23+ leukemic cells in patients with CLL.

scholarly journals Autoantibody-associated cross-reactive idiotype-bearing human B lymphocytes: distribution and characterization, including Ig VH gene and CD5 antigen expression

Blood ◽  
1991 ◽  
Vol 78 (6) ◽  
pp. 1503-1515 ◽  
Author(s):  
G Inghirami ◽  
DR Foitl ◽  
A Sabichi ◽  
BY Zhu ◽  
DM Knowles
Keyword(s):  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Cell Subset ◽  
Antigen Expression ◽  
Lymphocytic Leukemia ◽  
Cell Subpopulation ◽  
Lymphoid Tissues ◽  
Vh Gene

Abstract Monoclonal antibodies (MoAbs) specific for autoantibody associated cross-reactive idiotypes (CRIs) frequently recognize the Igs of neoplastic B cells in patients with chronic lymphocytic leukemia (CLL) and/or Waldenstrom's macroglobulinemia. Very little is known regarding the normal B cells expressing CRIs (CRI-positive B cells). Using a variety of MoAbs against CRIs we investigated the distribution and topographic localization of CRI-positive B cells in normal adult human lymphoid tissues. We found that CRI-positive B cells represent a significant B-cell subpopulation expressing surface IgM (greater than 90%), IgG (approximately 5%), or IgA (approximately 2%). CRI-positive B cells are homogeneously distributed throughout all lymphoid tissues, accounting for 10% to 15% of all B lymphocytes, with the exception of the thymus, in which they represent the predominant B cell population. Immunophenotypic studies showed (1) that a small subpopulation (3.7% +/- 0.8%) of CRI-positive B cells are activated in vivo, based on CD25 and CD38 antigen expression; and (2) that approximately 50% of CRI-positive B cells express the 67-Kd pan-T-lymphocyte CD5 antigen, suggesting that the CRI-positive B-cell subset and the recently described CD5-positive B-cell subset are closely related. This hypothesis is supported by the fact that CRI-positive B cells produce oligo or polyreactive Igs, which are a characteristic feature of CD5-positive B cells, and also by the fact that both B-cell subpopulations appear to use similar and restricted Ig VH gene family members.

scholarly journals Frequency of monoclonal B-cell lymphocytosis in relatives of patients with chronic lymphocytic leukemia

2016 ◽  
pp. 81-86
Author(s):  
Rossana Villegas Gracia ◽  
Catalina Franco Alzate ◽  
Javier Rendón Henao ◽  
José Domingo Torres Hernández ◽  
Patricia Elena Jaramillo Arbelaez
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
B Lymphocytes ◽  
B Lymphocyte ◽  
Chronic Lymphocytic Leukemia Patient ◽  
Lymphocytic Leukemia ◽  
Total Leukocyte Count ◽  
Female Participant ◽  
Color Flow ◽  
The One

Introduction: Monoclonal B-cell lymphocytosis is a symptom free condition characterized by the circulation of small clonal population of B lymphocytes in peripheral blood (less than 5x109/L) expressing an immunophenotype similar to chronic lymphocytic leukemia. Different studies based on big hospital series have manifested a higher risk in subjects with monoclonal B-cell lymphocytosis to progress to a chronic lymphocytic leukemia. The behavior of this hematologic entity is unknown therefore its frequency in sporadic chronic lymphocytic leukemia patient relatives was determined. Methods: Transversal descriptive study, 8 color flow cytometry was performed using two of the tubes of the Euro Flow recommended panel, with modifications, for the diagnose of chronic lymphoproliferative disorders of B lymphocytes; besides, a fluorescence in situ hybridization was performed. univariate and bivariate analyses of the information were performed. Results: Monoclonal B-cell lymphocytosis frequency found in 51 analyzed relatives was 2%, it was a female participant, 59 years old, with a total leukocyte count of 7.7x109/L and a B lymphocyte count of 0.124x109/L; from these, 0.04x109/L were clonal cells with restrictions of the kappa light chain. Rearrangements of the IGH gene (14q32) were found. Conclusion: Monoclonal B-cell lymphocytosis was detected in one relative of a patient with sporadic chronic lymphocytic leukemia in a frequency similar to the one reported in general population.

AICAR Induces Apoptosis In B Lymphocytes From Balb/c Mice and Its Effect In Chronic Lymphocytic Leukemia Cells Is Synergic or Additive with Current Chemotherapy

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1815-1815
Author(s):  
Diana M González-Gironès ◽  
Antonio F Santidrián ◽  
Daniel Iglesias-Serret ◽  
Ana M Cosialls ◽  
Alba Pérez-Perarnau ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Lymphocytes ◽  
Cytotoxic Effect ◽  
Alkylating Agents ◽  
Peripheral Lymphocyte ◽  
Point Of View ◽  
Lymphocytic Leukemia ◽  
Lymphocyte Population ◽  
Clinical Phase

Abstract Abstract 1815 AICAR (5-aminoimidazole-4-carboxamide riboside or acadesine) induces apoptosis in chronic lymphocytic leukemia (CLL) cells, without affecting primary T lymphocytes (Campàs et al, Bood 2003). Available treatments for this disease generally induce remission, although nearly all patients relapse and CLL remains incurable. Thus, AICAR is a promising drug for the treatment of this B-cell neoplasm. It has been recently published that AICAR induces apoptosis by a p53- and AMPK-independent mechanism through upregulation of BIM and NOXA in CLL cells (Santidrián&González-Gironès et al, Blood in press). A clinical phase I/II study of AICAR is currently being conducted in CLL patients (http://clinicaltrials.gov/ct2/NCT00559624 ). This clinical study has shown that AICAR plasmatic levels in the micro molar range are achievable and safe when CLL patients are treated with the drug. In vivo assays were performed in mice to analyze the effects of AICAR on the peripheral lymphocyte population. Thus, 0.5 mg/g AICAR was administered intraperitoneally to Balb/c mice every 12 hours and every day blood was collected from the tail of treated (n = 3) and untreated (n = 3) mice. Significant differences (p< .05) were observed between control and treated groups in the number of lymphocytes from day 3 to 6 while the number of total leucocytes did not change. From day 4 the peripheral lymphocyte population started to recover and mice were sacrificed at day 8. In addition, AICAR induced a significant reduction (p< .05) on the percentage of B cells from day 3 to 5. Therefore, AICAR is effective in vivo decreasing the number of peripheral B lymphocytes. From the therapeutic point of view, it is interesting to analyze whether AICAR could synergize with the cytotoxic activity of the current chemotherapy used in CLL patients. Thus, cells from CLL patients (n = 4) were treated with AICAR (0.125, 0.25, 0.5 and 1 mM) and/or dexamethasone (1, 2.5, 5 and 10 μM), fludarabine (0.3, 0.6, 1.5 and 3 μM), chlorambucil (1.25, 2.5, 5 and 10 μM), mafosfamide (the active metabolite of cyclophosphamide) (0.25, 0.5, 1 and 2 μg/mL), rituximab (10, 25, 50 and 100 μg/mL) or alemtuzumab (1.25, 2.5, 5 and 10 μg/mL). The cytotoxic effect of the alkylating agents chlorambucil and mafosfamide was synergic or additive with the effect of AICAR in CLL cells depending on the concentration used of both drugs. The glucocorticoid dexamethasone synergized with AICAR in half of the samples analyzed. As for the nucleoside analogue fludarabine and the monoclonal antibodies rituximab and alemtuzumab, their apoptotic effect was additive with AICAR at some concentrations. Together, AICAR induces apoptosis in B lymphocytes from Balb/c mice when administered intraperitoneally and its cytotoxic effect in CLL cells is synergic or additive with the most common chemotherapy used in CLL treatment. Disclosures: de Frias: Advancell: Employment. Campàs:Advancell: Employment.

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