Overexpression of the CXCR5 Chemokine Receptor, and Its Ligand, B Cell-Activating Chemokine-1 (BCA-1/CXCL13) in B Cell Chronic Lymphocytic Leukemia.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2948-2948
Author(s):  
Andrea Bürkle ◽  
Jan A. Burger
Keyword(s):  
Dendritic Cells ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Healthy Volunteers ◽  
B Lymphocytes ◽  
Surface Expression ◽  
Lymphocytic Leukemia ◽  
Lymphoid Tissues ◽  
Follicular Dendritic Cells

Abstract The chemokine B cell-activating chemokine-1 (BCA-1/CXCL13) is an important homing factor for lymphocytes to B cell zones of secondary lymphoid tissues. CXCL13 acts through its cognate receptor, CXCR5. Normal, mature B cells and a subset of memory T cells express CXCR5 chemokine receptors and migrate in response to BCA-1. However, BCA-1 displays a preferential chemotactic activity for B1 B cells when compared to “normal” B2 B cells. Because B lymphocytes from patients with Chronic Lymphocytic Leukemia (B-CLL) are in several aspects comparable to murine B1 cells, we hypothesized that the CXCR5-CXCL13 axis may be highly active in CLL. Initially, we noticed that CLL cells express functional CXCR5 receptors that induce actin polymerization, CXCR5 endocytosis, chemotaxis, and a prolonged activation of p44/42 MAP kinases. In addition, we examined CXCR5 surface expression in a series of CLL patients by flow cytometry and compared the results with normal B cells, or other leukemic B cell lymphoma. In CLL, leukemia B cells expressed significantly higher surface expression of CXCR5 (mean fluorescence intensity ratio/MFIR: 121 ± 9 (±SEM), n = 26) than circulating, CD19 positive B cells from healthy volunteers (CXCR5-MFIR: 69.9 ± 5.4, n = 11, p = 0.002). Neoplastic B cells from other leukemic B cell lymphomas displayed low surface CXCR5 expression (MFIR 19.7 ± 5.9, n = 11). Serum levels of CXCL13 were evaluated by ELISA. Sera from CLL patients displayed significantly higher levels of CXCL13 (mean ± SEM: 170.1 ± 21.5 pg/ml, n = 22) when compared to sera from healthy volunteers (mean ± SEM: 70.7 ± 5.2 pg/ml, n = 10, p = 0.004). Follicular dendritic cells (FDC) have been considered the main source of CXCL13 in secondary lymphoid tissues, thereby attracting T and B lymphocytes for cognate interactions. Surprisingly, we did not detect significant levels of CXCL13 in supernatants of HK follicular dendritic cells, that previously were demonstrated to protect CLL cells from apoptosis (Pedersen &Reed, Blood.2002;100:1795–801). In contrast, high levels of CXCL13 were detected in supernatants of CLL cell cultures in the presence of nurselike cells (NLC). In NLC cultures, CXCL13 levels were 610 ± 129.8 pg/ml (mean ± SEM, n = 4), whereas FDC supernatants contained 0.22 ± 0 pg/ml CXCL13 (mean ± SEM, n = 2). Because of these high CXCL13 levels in NLC cultures, we examined CXCR5 downregulation on CLL B cells in NLC co-cultures. When compared to freshly isolated CLL B cells, CLL cells from NLC cultures express significantly lower surface CXCR5. CXCR5 MFIR of CLL cells from NLC co-cultures was 7 ± 0.9, n = 4, compared to a CXCR5 MFIR of 91.6 ± 12 for freshly isolated CLL cells the same patients (mean ± SEM, n = 4, p = 0.000). These data indicate that high levels of bioactive CXCL13 are released in NLC cultures that stimulate cognate CXCR5 receptors on CLL B cells and induce signaling cascades, such as p44/42 MAPK, that induce prolonged survival. As such, this study provides a novel insight into interactions between CLL cells and their microenvironment within lymphoid tissues.

Inhibition of JAK2/STAT3 Pathway Leads to Apoptosis in Chronic Lymphocytic Leukemia Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2023-2023 ◽  
Author(s):  
Filippo Severin ◽  
Federica Frezzato ◽  
Veronica Martini ◽  
Flavia Raggi ◽  
Valentina Trimarco ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Cell Viability ◽  
B Cell ◽  
B Lymphocytes ◽  
Sh2 Domain ◽  
Lymphocytic Leukemia ◽  
Lymphoid Tissues ◽  
Stat3 Phosphorylation ◽  
Jak2 Inhibition

Abstract INTRODUCTION Chronic Lymphocytic Leukemia (CLL) is characterized by the accumulation of mature clonal CD19+/CD5+/CD23+ B lymphocytes in peripheral blood, bone marrow, and lymphoid tissues. Despite their in vivo prolonged lifespan due to intrinsic defects, CLL leukemic cells rapidly undergo spontaneous apoptosis in vitro, highlighting the need of extrinsic signals delivered by the microenvironment. Several molecules, including those released by mesenchymal stromal cells (MSCs), signal through JAK (Janus kinases)-STAT (Signal Transducers and Activators of Transcription) pathways. We particularly focused on the JAK2/STAT3 axis since Interleukin-6 (IL-6), one of the most abundant cytokines released in the CLL microenvironment, is the key ligand of the receptor triggering this pathway. The deregulation of JAK2/STAT3 axis may lead to aberrant activation of STAT3 and, as a result, to tumor development in hematopoietic cells. METHODS B cells were collected from 12 controls and 46 CLL patients. Purified cells (2x106cells/ml) were cultured, and treated with AG490 (10, 50 and 100μM), AZD1480 (1, 4 and 10μM), Fedratinib (1, 5 and 10μM), and Ruxolitinib (0.313, 2.5 and 10μM) (which are JAK2 inhibitors), and the STAT3 inhibitor Stattic (5, 7.5, and 10μM) for 24, 48 and 72h. Experiments with AG490 and Stattic were performed with/without MSCs. STAT3 expression and phosphorylation were evaluated by Western Blotting (WB) and Flow Cytometry (FC), and its localization was analyzed by confocal microscopy and subcellular fractionation. CLL and normal B cell viability was tested by FC with Annexin V/PI test. RESULTS We demonstrated that STAT3 was highly expressed in malignant B cells with respect to normal B lymphocytes. As far as STAT3 phosphorylation at Tyr705, that is an essential step for STAT3 activation, we demonstrated a constitutive phosphorylation in CLL cells by FC and WB analyses, although in some patients STAT3 Tyr705 phosphorylation is barely detected. We also pointed out that the in vitroincubation of leukemic B cells with AG490 and Stattic and Fedratinib, induces a dose-dependent apoptosis of CLL B cells. However, the tested doses of Ruxolitinib and AZD1480 did not seem to CLL B cell viability but only STAT3 phosphorylation. Both AG490 and Stattic were able to bypass the microenvironmental protection when neoplastic B cells were co-cultured with MSCs. STAT3 Tyr705 localization was analyzed in normal and leukemic B cells by a subcellular protein fractionation. We separated nuclei from cytosol, detecting STAT3 Tyr705 both in the cytosolic and in the nuclear fractions of CLL B cells. We showed that AG490 and Fedratinib treatment on CLL cells can mediate other effects: i) SHP-1 activity is turned on by JAK2 inhibition, decreasing its phosphorylation at Ser591; ii) AG490 administration inactivates protein Lyn, reducing the phosphorylation in its active site at Tyr396. Lyn, a Tyr-kinase, and SH2-domain containing Tyrosine Phosphatase (SHP-1), a Tyr-phosphatase, are both involved in the prolonged lifespan of neoplastic CLL cells. To confirm the link between JAK2 inhibition by AG490 and Lyn dephosphorylation, we added sodium orthovanadate (Na3VO4, 100 μM), a phosphatase inhibitor, to cell culture to restore Lyn activation (resulting from the inactivation of SHP-1 phosphatase); as a result, Lyn Tyr396 phosphorylation was restored. On the contrary, the treatment of CLL cells with Stattic did not induce any change in SHP-1 status with respect to untreated cells since Stattic is effective on STAT3, that is a downstream protein with respect to JAK2. Since Stattic did not affect SHP-1 activation, it does not impact on Lyn activation/phosphorylation. CONCLUSIONS The ability of AG490 and Stattic to induce apoptosis in leukemic B cells bypassing the pro-survival stimuli provided by the tumor microenvironment and the Fedratinib effectiveness at low doses, represents a starting point for the development of new therapeutic strategies in CLL. This study also provides new insights for the investigation of the pathogenesis of CLL focusing the attention on the cross-talk between JAK/STAT and BCR/Lyn axes. Disclosures No relevant conflicts of interest to declare.

Access to Follicular Dendritic Cells Is a Pivotal Step in Murine Chronic Lymphocytic Leukemia B-cell Activation and Proliferation

2014 ◽  
Vol 4 (12) ◽  
pp. 1448-1465 ◽  
Author(s):  
Kristina Heinig ◽  
Marcel Gätjen ◽  
Michael Grau ◽  
Vanessa Stache ◽  
Ioannis Anagnostopoulos ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Cell Activation ◽  
Lymphocytic Leukemia ◽  
Follicular Dendritic Cells ◽  
B Cell Activation ◽  
Follicular Dendritic

Overexpression of the CXCR5 chemokine receptor, and its ligand, CXCL13 in B-cell chronic lymphocytic leukemia

Blood ◽  
2007 ◽  
Vol 110 (9) ◽  
pp. 3316-3325 ◽  
Author(s):  
Andrea Bürkle ◽  
Matthias Niedermeier ◽  
Annette Schmitt-Gräff ◽  
William G. Wierda ◽  
Michael J. Keating ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Actin Polymerization ◽  
Serum Levels ◽  
Lymphocytic Leukemia ◽  
Lymphoid Tissues ◽  
Accessory Cells ◽  
Mitogen Activated Protein ◽  
B1 Cells

Abstract CXCL13 is a homeostatic chemokine for lymphocyte homing and positioning within follicles of secondary lymphoid tissues, acting through its cognate receptor, CXCR5. Moreover, the CXCR5-CXCL13 axis plays a unique role in trafficking and homing of B1 cells. Here, we report that chronic lymphocytic leukemia (CLL) B cells express high levels of functional CXCR5. CXCR5 expression levels were similar on CLL B cells and normal CD5+ B cells, and higher compared with normal CD5− B cells, follicular B-helper T cells (TFH cells), or neoplastic B cells from other B-cell neoplasias. Stimulation of CLL cells with CXCL13 induces actin polymerization, CXCR5 endocytosis, chemotaxis, and prolonged activation of p44/42 mitogen-activated protein kinases. Anti-CXCR5 antibodies, pertussis toxin, and wortmannin inhibited chemotaxis to CXCL13, demonstrating the importance of Gi proteins and PI3 kinases for CXCR5 signaling. Moreover, CLL patients had significantly higher CXCL13 serum levels than volunteers, and CXCL13 levels correlated with β2 microglobulin. We detected CXCL13 mRNA expression by nurselike cells, and high levels of CXCL13 protein in supernatants of CLL nurselike cell cultures. By immunohistochemistry, we detected CXCL13+ expression by CD68+ macrophages in situ within CLL lymph nodes. These data suggest that CXCR5 plays a role in CLL cell positioning and cognate interactions between CLL and CXCL13-secreting CD68+ accessory cells in lymphoid tissues.

B-Cell Receptor Signaling Enhances Migration of B-Cell Chronic Lymphocytic Leukemia Cells in Response to the Chemokine Stromal Cell-Derived Factor-1 (SDF-1/CXCL12).

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1187-1187
Author(s):  
Jan A. Burger ◽  
Myriam Krome ◽  
Andrea Bürkle ◽  
Tanja N. Hartmann
Keyword(s):  
Dendritic Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Stromal Cells ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Follicular Dendritic Cells ◽  
Accessory Cells ◽  
Bcr Signaling

Abstract There is growing evidence that the microenvironment confers survival signals to Chronic Lymphocytic Leukemia (CLL) B-cells that may result in disease progression and resistance to therapy. In the marrow or secondary lymphoid tissues, CLL cells are in close contact with non-tumoral accessory cells, such as mesenchymal stromal cells or nurselike cells. We previously characterized SDF-1 (CXCL12) as a central mediator for CLL cell migration and interaction with the protective microenvironment. Constitutive secretion of CXCL12 attracts CLL cells to stroma or NLC through its cognate receptor, CXCR4. These accessory cells protect CLL cells from spontaneous or drug-induced apoptosis, which is contact-dependent and partially mediated by CXCL12. B-cell receptor (BCR) signaling has been considered another important regulator of CLL cell survival. Typically, CLL cell that lack somatic mutations in the immunoglobulin (Ig) variable region (V) genes and display high levels of the tyrosine kinase ZAP-70 strongly responds to anti-IgM stimulation. Because both, CXCL12 stimulation and BCR signaling may represent important mechanism for maintenance of CLL cell within the microenvironment, we examined whether anti-IgM stimulation affects CXCL12 responses in correlation with the ZAP-70 status. BCR signaling was modulated either by crosslinking the BCR with IgM or by blocking the tyrosine kinase Syk. Effective BCR cross-linking with anti-IgM antibodies was demonstrated by phosphorylation of Syk and p44/42 MAP kinase. In ZAP-70 positive cells, BCR crosslinking resulted in a robust activation of Syk, p44/42 MAP kinases, and protein kinase B (Akt). ZAP-70 negative CLL cells displayed a weaker activation of p44/42 upon IgM crosslinking. Pretreatment of CLL cells with anti-IgM resulted in an enhanced calcium mobilization upon CXCL12 stimulation. This was not due to changes in surface expression of CXCR4. Accordingly, Syk inhibition by piceatannol resulted in a loss of calcium response upon CXCL12 stimulation. Furthermore, anti-IgM stimulation significantly increased CLL cell chemotaxis towards CXCL12 1.4 ± 1.2fold (n=9, p=0.027), and Syk inhibition by piceatannol decreased chemotaxis to 0.6 ± 0.2fold of controls (n=8). In these experiments, we could not detect differences between ZAP-70 positive or negative cells. However, there was a strong difference regarding the spontaneous, CXCL12-dependent migration of CLL cells beneath marrow stromal cells (pseudoemperipolesis). BCR crosslinking significantly increased pseudoemperipolesis of ZAP-70 expressing CLL cells 13.4 ± 21.0fold (n=7, p=0.043), whereas there was no significant increase in pseudoemperipolesis of ZAP-70 negative cells (1.4 ± 0.2fold increase, n=8). Syk inhibition by piceatannol significantly decreased the pseudoemperipolesis of ZAP-70 positive as well as ZAP-70 negative CLL cells to 0.4 ± 0.07 of controls (n=5, p=0.043). Interestingly, spontaneous migration of CLL cells beneath follicular dendritic cells (HK cells) was also significantly enhanced by anti-IgM stimulation, in particular in ZAP-70 positive cases. In summary, BCR signaling enhances calcium mobilization, CLL cell migration to CXCL12, and pseudoemperipolesis beneath marrow stroma or follicular dendritic cells. These data suggest that BCR stimulation co-operates with CXCL12 for localization and/or maintenance of CLL cells within distinct tissue microenvironments.

Different Expression of FcgammaRIIb in Chronic Lymphocytic Leukemia and Human Normal B Lymphocytes

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3134-3134
Author(s):  
Carol Moreno ◽  
Rajendra Damle ◽  
Sonia Jansa ◽  
Gerardo Ferrer ◽  
Pau Abrisqueta ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
B Lymphocytes ◽  
Surface Membrane ◽  
Memory B Cells ◽  
Lymphocytic Leukemia ◽  
Cd38 Expression ◽  
B Cell Subsets

Abstract The Fcgamma receptors (FcγRs) are a family of molecules that modulate immune responses. FcγRIIb is an inhibitory FcγR that bears immunoreceptor tyrosine-based inhibitory motifs which transduce inhibitory signals on coligation with the surface membrane Ig of the B-cell antigen receptor (BCR). The role of FcγRIIb in controlling B cell activation through inhibition of BCR signaling has been extensively studied in animal models. Nevertheless, data on FcγRIIb are scant in human normal and neoplastic B cells, this being due to the lack of a specific antibody for human FcγRIIb. Consequently, there is little information on this receptor in chronic lymphocytic leukemia (CLL). Considering the activated nature of CLL cells and the central role of the BCR in the biology of the disease, studies of FcγRs are warranted. We used a novel specific mAb directly conjugated with Alexa 488 fluorophore that solely reacts with the human FcγRIIb (MacroGenics, Inc.) to investigate the receptors expression on CLL and normal human B cells. The study population included 84 patients with CLL and 24 age- and sex-matched controls. FcγRIIb expression was assessed as the mean fluorescence intensity (MFI) of surface membrane staining. In CLL cells, FcγRIIb was measured on CD19+CD5+ cells in combination with CD38, CD49d or CD69. Normal B cells were immunostained for CD19, CD5, IgD and CD38 expression and B cell subsets: naïve (IgD+CD38−), activated (IgD+CD38+) and memory B cells (IgD−CD38−) were studied for their relative expression of FcγRIIb. FcγRIIb expression was found significantly higher in naïve B cells compared to activated and memory B cells [median MFI: 17420 (11960–21180) vs. 11.140 (7899–16970) and 11.830 (6984–17100); p<0.001]. Significant differences were also observed between CD5− and CD5+ normal B cells. In contrast, FcγRIIb expression was lower in CLL cells than in CD5+ and CD5− normal B lymphocytes [median MFI: 6901(1034–42600), 10180 (5856–14820) and 12120 (7776–16040); p<0.05)]. Interestingly, FcγRIIb expression was variable within individual CLL clones, this being higher in CD38+ and CD49d+ cells than in CD38− and CD49d− cells (p<0.05). Furthermore, the highest density of FcγRIIb was observed on those cells which coexpressed CD38 and CD49d. In contrast, no significant differences were observed between FcγRIIb and the expression of the activation antigen CD69. Although CD69 and CD38 expression was significantly higher on unmutated IGHV cases, no correlation was found between FcγRIIb levels and IGHV mutational status. Similarly, there was no correlation between FcγRIIb and other poor prognostic variables such as ZAP-70 (≥20%), CD38 (≥ 30%) or high risk cytogenetics. Nevertheless, cases with ≥ 30% CD49d+ cells had higher FcγRIIb expression than those with <30% CD49d+ cells (p=0.006). The findings presented in this study suggest a hierarchy of FcγRIIb expression in normal B-cells, CLL cells and their subpopulations: circulating normal CD5− B cells > circulating normal CD5+ B cells > circulating CD5+ CLL B cells. In addition, although FcγRIIb is present on all normal B cell subsets its expression is higher in naïve B cells. Furthermore, in CLL FcγRIIb density is greater in CD38+ and CD49d+ cells within the clone. Although CD49d and FcγRIIb on CLL clones is linked in a direct manner, there is no relationship with FcγRIIb density and IGHV mutations, ZAP-70, CD38 and unfavorable cytogenetic markers. Finally, the relationship between FcγRIIb expression on CLL cells and functional responses to BCR and other receptor-mediated signals deserve further investigation.

Role Of Lyn Kinase In The Pathogenesis Of Chronic Lymphocytic Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 668-668
Author(s):  
Phuong-Hien Nguyen ◽  
Nina Reinart ◽  
Michael Hallek
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Conflicts Of Interest ◽  
Myeloid Cells ◽  
Lymphocytic Leukemia ◽  
Negative Regulator ◽  
Lymphoid Tissues ◽  
Malignant Cells ◽  
Deficient Mice

Abstract The Src family kinase Lyn is predominantly expressed in B cells and plays a central role in initiating B cell receptor (BCR) signaling. Lyn is associated with BCR complexes and is renowned for its role in B cell activation and proliferation. Active Lyn contributes to positive regulation of signalling through tyrosine phosphorylation of components of the BCR. Intriguingly, Lyn was also shown as a negative regulator of BCR signal transduction. Lyn plays an essential role in negative regulation of signalling through its unique ability to phosphorylate immunoreceptor tyrosine based inhibition motifs (ITIM) in inhibitory cell surface receptors. ITIM phosphorylation induces the recruitment of inhibitory phosphatases such as SHP-1/2 and SHIP-1, which attenuate BCR signalling. Lyn-deficient mice have reduced number of B cells and increased numbers of myeloid progenitors. It was reported that expression and activity of Lyn in human chronic lymphocytic leukemia (CLL) is elevated compared to healthy B cells. Besides, higher levels of Lyn are associated with a shorter treatment-free survival of CLL patients. This rises up a hypothesis about Lyn’s significant role in B cell tumorigenesis, malignant transformation of B cells, and the balance between myeloid cells and B lymphocytes. We generated Eµ-TCL1 transgenic LYN-deficient mice (TCL1+/wtLYN-/-) and monitored them in order to identify the population of malignant B cells and to characterize the development of malignant cells in these mice in comparison with Eµ-TCL1 transgenic mice (TCL1+/wtLYNwt/wt). In comparison to TCL1+/wtLYNwt/wt mice, TCL1+/wtLYN-/- mice show a significantly reduced number of malignant B cells in the peripheral blood, as well as a reduced leukocyte count. Besides, TCL1+/wtLYN-/- mice have significantly decreased infiltration of malignant B cells in lymphoid tissues such as spleen, liver, lymph node and bone marrow. This result is also resembled in a hepato-splenomegaly in the TCL1+/wtLYNwt/wt mice. These mice develop severe splenomegaly and hepatomegaly due to infiltration of malignant cells, while TCL1+/wtLYN-/- mice do not develop hepatomegaly. The non-transgenic LYN-/- control mice develop splenomegaly due to infiltration of myeloid cells. Although TCL1+/wtLYN-/- mice have hindered development of TCL1-induced CLL, preliminary data suggest it is not only due to LYN-deficiency in B cell compartment of these mice. Indeed, B cell of TCL1+/wtLYN-/- mice show enhanced proliferation and better survival ex vivo compared to TCL1+/wtLYNwt/wt mice. Notably, TCL1+/wtLYN-/- mice developed a skewed microenvironment which might contribute to CLL down regulation. LYN-/- microenvironment, particularly in aged mice, does not support engraftment of TCL1-induced leukemic B cell as well as LYNwt/wt mice in our transplantation model. These results point to a complex regulation of Lyn signalling in CLL involving not only leukemic cells but also cells of the micromillieu, that needs further investigation. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Immunoglobulin secretory function of B cells from untreated patients with chronic lymphocytic leukemia and hypogammaglobulinemia: role of T cells

Blood ◽  
1983 ◽  
Vol 62 (4) ◽  
pp. 767-774 ◽  
Author(s):  
LA Fernandez ◽  
JM MacSween ◽  
GR Langley
Keyword(s):  
T Cells ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
B Lymphocytes ◽  
Peripheral Blood ◽  
Cell Function ◽  
Lymphocytic Leukemia ◽  
Suppressor Activity ◽  
Normal Peripheral Blood

Abstract The mechanism of the hypogammaglobulinemia in patients with chronic lymphocytic leukemia (CLL) was studied by determining the generation of specific immunoglobulin-secreting cells in response to mitogen and antigen stimulation in culture. Normal peripheral blood B lymphocytes from 18 normal subjects cocultured with equal numbers of autologous T cells generated cells secreting 2,542 +/- 695 IgG, 2,153 +/- 615 IgA, and 2,918 +/- 945 IgM. Normal B lymphocytes cocultured with normal allogeneic T cells generated similar numbers. However, B lymphocytes from patients with chronic lymphocytic leukemia cocultured with T cells from the same patient generated only 0.5% as many cells secreting IgG and 11% and 23% as many secreting IgA and IgM, respectively. The reason for this markedly defective generation of immunoglobulin-secreting cells was investigated by evaluating T-helper, T-suppressor, and B-cell function using B cells from tonsil and T and B cells from peripheral blood of normal and leukemic individuals. T cells from patients with chronic lymphocytic leukemia provided somewhat greater help than did normal T cells to normal peripheral blood B cells and normal help to tonsil B cells, whether stimulated with mitogen or antigen. T cells from patients with chronic lymphocytic leukemia did not demonstrate increased suppressor function compared to normals with B cells from normal peripheral blood. The hypogammaglobulinemia in these patients therefore was associated with a markedly defective generation of immunoglobulin secreting cells, and as there was normal or increased T- cell helper activity without excessive suppressor activity, it seems likely that this was due to an intrinsic B-cell defect.

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 Analysis of signal transduction in B chronic lymphocytic leukemia cells

Blood ◽  
1988 ◽  
Vol 71 (5) ◽  
pp. 1461-1469
Author(s):  
HG Drexler ◽  
MK Brenner ◽  
E Coustan-Smith ◽  
SM Gignac ◽  
AV Hoffbrand
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
B Cells ◽  
Protein Kinase ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
B Lymphocytes ◽  
Lymphocytic Leukemia ◽  
Receptor Expression ◽  
Kinase C

We report here experiments on the analysis of cellular signal transduction in a series of patients with chronic B cell disorders (B cell chronic lymphocytic leukemia [B-CLL] and prolymphocytic leukemia). We compared the response of the leukemic cells with primary external signals (interleukin 2 [IL-2] or B cell differentiation factors [BCDF or IL-6]) with their response to secondary inducers (the phorbol ester (12–O-tetradecanoylphorbol-13-acetate [TPA] or the calcium ionophore A23187) that circumvent the first part of the signal transduction pathway by directly activating the key enzyme protein kinase C. One BCDF was synthesized by mitogen-activated peripheral blood B lymphocytes; a second BCDF was constitutively produced by the human bladder carcinoma cell line T24. Changes in morphology, Tac (IL-2 receptor) expression, RNA synthesis measured by 3H-uridine uptake, and immunoglobulin production tested by enzyme-linked immunosorbent assay were used as parameters of successful signal transduction. TPA alone and TPA plus A23187 (synergistically) effectively initiated differentiation in all the leukemia cases. Neither IL-2 nor BCDF (singly or in combinations) caused equivalent responses. On the other hand, IL-2 and BCDF produced a substantial differentiation effect on normal B lymphocytes. Our data suggest that (a) B-CLL cells are able to respond to direct stimulation of the second messenger pathway (through protein kinase C) but not to the physiological stimuli IL-2 or BCDF; (b) the defect in signal transduction appears to be located upstream of protein kinase C (a possible candidate is a G protein); (c) malignant B cells may spontaneously or after treatment with inducers express the IL- 2 receptor (Tac antigen) in the absence of a functional differentiating response to IL-2; and (d) signs of proliferation/differentiation in B- CLL samples after incubation with IL-2 or BCDF might be due to contamination of the cell populations with residual normal B cells.

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