scholarly journals MiR-181b in Chronic Lymphocytic Leukemia B Cells Is Regulated By Cellular Interaction with CD4+ T Cells and Increases the CTL Toxicity Versus the Leukemic Clone

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4134-4134
Author(s):  
Mirco di Marco ◽  
Serena Veschi ◽  
Rosa Visone ◽  
Giuseppe Leone ◽  
Paola Lanuti ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Cd4 T Cells ◽  
Lymphocytic Leukemia ◽  
Healthy Donors ◽  
Leukemic Clone

Abstract Clinical progression of chronic lymphocytic leukemia (CLL) is characterized by gradual reduction of the ratio T/B cells, along with immune cell dysfunction due, at least in part, to T cell defects, such as decreased expression of CD40L and reduced signaling via the TCR CD3. This compromise the ability of T cells to respond and to eliminate leukemic cell from CLL patients. Enhanced activation of either allogenic or autologous T cells can drive the death of CLL cells in vitro and in human subjects. Changes in microRNAs expression also characterize clinical progression of CLL with a strong decrease of miR-181b/a and miR-130a associated with the more aggressive phase of the disease. The miR-181b targets anti-apoptotic proteins, such as BCL-2 and MCL1 and its expression correlates with those protein levels in CLL. In this study we demonstrate that the expression of those microRNAs in CLL-B cells, are regulated by T cells. We co-cultured allogenic pure CLL-B cells with either activated (CD2, CD3 and CD28 antibodies, used to mimic antigen-presenting cells) or not activated CD4+ T cells from healthy donors. We observed a significant increase of mir-181b/a and miR-130a expression in CLL B-cells after co-culture with activated CD4+ T cells in 8 out of 11 cases. A significant increase of these miRs was also determined in purified CLL B-cells after 4 days activation of peripheral blood mononuclear cells (PBMCs) from CLL patients, even if in minor rate. By the use of specific antibodies, co-culture with Hela CD40 expressing cells and transwell experiments, we established that this effect is a T/B contact-dependent signaling mediated through CD40L-CD40 interaction. We determine that increased expression of the 3 miRs occurs at the transcriptional level. Since the expression of miR-181b showed the most significant variation in previous experiments it was selected for further analyses. We next investigated the in vivo role of the miR-181b in highly immunodeficient mice. The CLL cell line, MEC-01, infected with either the LV-miR-181b_coGFP or the LV-CTRL_coGFP was intravenously inoculated in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. Mice were sacrificed after 4 weeks and assayed for percentage of GFP+ cells in bone marrow and spleen compartments. The miR-181b did not show any specific effect into the leukemic clone. However when the same cells were inoculated in an environment hosting mature T cells, miR-181b consistently influences the death of leukemic cells (Fig 1B), suggesting that T cells are required to potentiate the apoptotic role of this miRNA. To explain what we observed in vivo, we mixed in vitro MEC-01 infected with either the LV-miR-181b or the LV-CTRL and CD8+ T cells from healthy donors. After few hours of contact T cells showed stronger cytotoxic effect on MEC-01 carrying miR-181b as compared to the control. Mixed lymphocyte reaction CD40L-activated CLL and T cells is used to generate effector CTLs. Therefore we grew T cell with CD40L-activated MEC-01 in which the expression of miR-181b was either shut down by lentiviral vector or unchanged as control. After one week, we monitored by cytofluorimetry the CD38 surface marker on T cells since its expression has been associated with more active CTLs and, by ELISA, the release of IL-10, the inhibitor of the potent inducer of CTLs INF-g. We demonstrate that activated MEC-01 with higher expression of miR-181b leads to an increase of the cell number expressing CD38 and this was accompanied by a reduced release of IL-10 from B cells through down-regulation of c-FOS, which we show to be target of the miR-181b and to promote the transcription of the IL-10. In conclusion, our data suggest a role of the miR-181b in the immune response against CLL-B cells. We show that an efficient activation of CD4+ T cells through CD3-complex pathway and a right CD40L-CD40 interaction lead to a significant increase of the some miRNAs deregulated over the progression of chronic lymphocytic leukemia, namely miR-181b. This miRNA potentiates the cytotoxicity of T cells favoring the killing of the leukemic clone. Disclosures No relevant conflicts of interest to declare.

scholarly journals CD4+ T cells sustain aggressive chronic lymphocytic leukemia in Eμ-TCL1 mice through a CD40L-independent mechanism

2021 ◽  
Vol 5 (14) ◽  
pp. 2817-2828
Author(s):  
Matteo Grioni ◽  
Arianna Brevi ◽  
Elena Cattaneo ◽  
Alessandra Rovida ◽  
Jessica Bordini ◽  
...  
Keyword(s):  
T Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Antigen Specificity

Abstract Chronic lymphocytic leukemia (CLL) is caused by the progressive accumulation of mature CD5+ B cells in secondary lymphoid organs. In vitro data suggest that CD4+ T lymphocytes also sustain survival and proliferation of CLL clones through CD40L/CD40 interactions. In vivo data in animal models are conflicting. To clarify this clinically relevant biological issue, we generated genetically modified Eμ-TCL1 mice lacking CD4+ T cells (TCL1+/+AB0), CD40 (TCL1+/+CD40−/−), or CD8+ T cells (TCL1+/+TAP−/−), and we monitored the appearance and progression of a disease that mimics aggressive human CLL by flow cytometry and immunohistochemical analyses. Findings were confirmed by adoptive transfer of leukemic cells into mice lacking CD4+ T cells or CD40L or mice treated with antibodies depleting CD4 T cells or blocking CD40L/CD40 interactions. CLL clones did not proliferate in mice lacking or depleted of CD4+ T cells, thus confirming that CD4+ T cells are essential for CLL development. By contrast, CD8+ T cells exerted an antitumor activity, as indicated by the accelerated disease progression in TCL1+/+TAP−/− mice. Antigen specificity of CD4+ T cells was marginal for CLL development, because CLL clones efficiently proliferated in transgenic mice whose CD4 T cells had a T-cell receptor with CLL-unrelated specificities. Leukemic clones also proliferated when transferred into wild-type mice treated with monoclonal antibodies blocking CD40 or into CD40L−/− mice, and TCL1+/+CD40−/− mice developed frank CLL. Our data demonstrate that CD8+ T cells restrain CLL progression, whereas CD4+ T cells support the growth of leukemic clones in TCL1 mice through CD40-independent and apparently noncognate mechanisms.

scholarly journals Immunomodulatory effects of different intravenous immunoglobulin preparations in chronic lymphocytic leukemia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ana Colado ◽  
Esteban Enrique Elías ◽  
Valeria Judith Sarapura Martínez ◽  
Gregorio Cordini ◽  
Pablo Morande ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
T Cell Activation ◽  
Cell Activation ◽  
Lymphocytic Leukemia ◽  
Immunomodulatory Effects ◽  
Immunoglobulin Preparations

AbstractHypogammaglobulinemia is the most frequently observed immune defect in chronic lymphocytic leukemia (CLL). Although CLL patients usually have low serum levels of all isotypes (IgG, IgM and IgA), standard immunoglobulin (Ig) preparations for replacement therapy administrated to these patients contain more than 95% of IgG. Pentaglobin is an Ig preparation of intravenous application (IVIg) enriched with IgM and IgA (IVIgGMA), with the potential benefit to restore the Ig levels of all isotypes. Because IVIg preparations at high doses have well-documented anti-inflammatory and immunomodulatory effects, we aimed to evaluate the capacity of Pentaglobin and a standard IVIg preparation to affect leukemic and T cells from CLL patients. In contrast to standard IVIg, we found that IVIgGMA did not modify T cell activation and had a lower inhibitory effect on T cell proliferation. Regarding the activation of leukemic B cells through BCR, it was similarly reduced by both IVIgGMA and IVIgG. None of these IVIg preparations modified spontaneous apoptosis of T or leukemic B cells. However, the addition of IVIgGMA on in vitro cultures decreased the apoptosis of T cells induced by the BCL-2 inhibitor, venetoclax. Importantly, IVIgGMA did not impair venetoclax-induced apoptosis of leukemic B cells. Overall, our results add new data on the effects of different preparations of IVIg in CLL, and show that the IgM/IgA enriched preparation not only affects relevant mechanisms involved in CLL pathogenesis but also has a particular profile of immunomodulatory effects on T cells that deserves further investigation.

Evaluation of vecabrutinib as a model for non-covalent BTK/ITK inhibition for treatment of chronic lymphocytic leukemia

Blood ◽  
2021 ◽  
Author(s):  
Billy Michael Chelliah Jebaraj ◽  
Annika Müller ◽  
Rashmi Priyadharshini Dheenadayalan ◽  
Sascha Endres ◽  
Philipp M. Roessner ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Chronic Lymphocytic Leukemia ◽  
Inhibitory Effect ◽  
Lymphocytic Leukemia ◽  
Transfer Model ◽  
Treatment Benefit ◽  
Btk Inhibitors

Covalent Bruton tyrosine kinase (BTK) inhibitors such as ibrutinib have proven to be highly beneficial in the treatment of chronic lymphocytic leukemia (CLL). Interestingly, the off-target inhibition of IL-2-inducible T-cell kinase (ITK) by ibrutinib may also play a role in modulating the tumor microenvironment, potentially enhancing the treatment benefit. However, resistance to covalently binding BTK inhibitors can develop by a mutation in cysteine 481 of BTK (C481S), which prevents the irreversible binding of the drugs. In the present study we performed pre-clinical characterization of vecabrutinib, a next generation non-covalent BTK inhibitor, with ITK inhibitory properties similar to those of ibrutinib. Unlike ibrutinib and other covalent BTK inhibitors, vecabrutinib showed retention of the inhibitory effect on C481S BTK mutants in vitro, similar to that of wildtype BTK. In the murine Eµ-TCL1 adoptive transfer model, vecabrutinib reduced tumor burden and significantly improved survival. Vecabrutinib treatment led to a decrease in CD8+ effector and memory T-cell populations, while the naïve populations were increased. Of importance, vecabrutinib treatment significantly reduced frequency of regulatory CD4+ T-cells (Tregs) in vivo. Unlike ibrutinib, vecabrutinib treatment showed minimal adverse impact on activation and proliferation of isolated T-cells. Lastly, combination treatment of vecabrutinib with venetoclax was found to augment treatment efficacy, significantly improve survival and lead to favourable reprogramming of the microenvironment in the murine Eµ-TCL1 model. Thus, non-covalent BTK/ITK inhibitors such as vecabrutinib may be efficacious in C481S BTK mutant CLL, while preserving the T-cell immunomodulatory function of ibrutinib.

scholarly journals Defective T cell-mediated, isotype-specific immunoglobulin regulation in B cell chronic lymphocytic leukemia

Blood ◽  
1988 ◽  
Vol 71 (4) ◽  
pp. 1012-1020 ◽  
Author(s):  
JS Moore ◽  
MB Prystowsky ◽  
RG Hoover ◽  
EC Besa ◽  
PC Nowell
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Cell Activity ◽  
Lymphocytic Leukemia ◽  
Specific Immunoglobulin ◽  
Cell Chronic Lymphocytic Leukemia

The consistent occurrence of T cell abnormalities in patients with B cell chronic lymphocytic leukemia (B-CLL) suggest that the non- neoplastic host T cells may be involved in the pathogenesis of this B cell neoplasm. Because potential defects of immunoglobulin regulation are evident in B-CLL patients, we investigated one aspect of this by studying the T cell-mediated immunoglobulin isotype-specific immunoregulatory circuit in B-CLL. The existence of class-specific immunoglobulin regulatory mechanisms mediated by Fc receptor-bearing T cells (FcR + T) through soluble immunoglobulin binding factors (IgBFs) has been well established in many experimental systems. IgBFs can both suppress and enhance B cell activity in an isotype-specific manner. We investigated the apparently abnormal IgA regulation in a B-CLL patient (CLL249) whose B cells secrete primarily IgA in vitro. Enumeration of FcR + T cells showed a disproportionate increase in IgA FcR + T cells in the peripheral blood of this patient. Our studies showed that the neoplastic B cells were not intrinsically unresponsive to the suppressing component of IgABF produced from normal T cells, but rather the IgABF produced by the CLL249 host T cells was defective. CLL249 IgABF was unable to suppress IgA secretion by host or normal B cells and enhanced the in vitro proliferation of the host B cells. Size fractionation of both normal and CLL249 IgABF by gel-filtration high- performance liquid chromatography (HPLC) demonstrated differences in the ultraviolet-absorbing components of IgABF obtained from normal T cells v that from our patient with defective IgA regulation. Such T cell dysfunction may not be restricted to IgA regulation, since we have found similar expansion of isotype-specific FcR + T cells associated with expansion of the corresponding B cell clone in other patients with B-CLL. These data suggest that this T cell-mediated regulatory circuit could be significantly involved in the pathogenesis of B-CLL.

scholarly journals Dissecting the Prognostic Significance and Functional Role of Progranulin in Chronic Lymphocytic Leukemia

Cancers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 822 ◽  
Author(s):  
Lena Schulze-Edinghausen ◽  
Claudia Dürr ◽  
Selcen Öztürk ◽  
Manuela Zucknick ◽  
Axel Benner ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Prognostic Significance ◽  
Lymphocytic Leukemia ◽  
Cancer Associated Fibroblast ◽  
Survival Gene ◽  
Potential Use

Chronic lymphocytic leukemia (CLL) is known for its strong dependency on the tumor microenvironment. We found progranulin (GRN), a protein that has been linked to inflammation and cancer, to be upregulated in the serum of CLL patients compared to healthy controls, and increased GRN levels to be associated with an increased hazard for disease progression and death. This raised the question of whether GRN is a functional driver of CLL. We observed that recombinant GRN did not directly affect viability, activation, or proliferation of primary CLL cells in vitro. However, GRN secretion was induced in co-cultures of CLL cells with stromal cells that enhanced CLL cell survival. Gene expression profiling and protein analyses revealed that primary mesenchymal stromal cells (MSCs) in co-culture with CLL cells acquire a cancer-associated fibroblast-like phenotype. Despite its upregulation in the co-cultures, GRN treatment of MSCs did not mimic this effect. To test the relevance of GRN for CLL in vivo, we made use of the Eμ-TCL1 CLL mouse model. As we detected strong GRN expression in myeloid cells, we performed adoptive transfer of Eμ-TCL1 leukemia cells to bone marrow chimeric Grn−/− mice that lack GRN in hematopoietic cells. Thereby, we observed that CLL-like disease developed comparable in Grn−/− chimeras and respective control mice. In conclusion, serum GRN is found to be strongly upregulated in CLL, which indicates potential use as a prognostic marker, but there is no evidence that elevated GRN functionally drives the disease.

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.

scholarly journals Influenza virus-specific CD4+ T helper type 2 T lymphocytes do not promote recovery from experimental virus infection.

1994 ◽  
Vol 180 (4) ◽  
pp. 1273-1282 ◽  
Author(s):  
M B Graham ◽  
V L Braciale ◽  
T J Braciale
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Lymphocytes ◽  
Cd4 T Cells ◽  
Primary Role ◽  
T Helper ◽  
Helper Type

T lymphocytes play a primary role in recovery from viral infections and in antiviral immunity. Although viral-specific CD8+ and CD4+ T cells have been shown to be able to lyse virally infected targets in vitro and promote recovery from lethal infection in vivo, the role of CD4+ T lymphocytes and their mechanism(s) of action in viral immunity are not well understood. The ability to further dissect the role that CD4+ T cells play in the immune response to a number of pathogens has been greatly enhanced by evidence for more extensive heterogeneity among the CD4+ T lymphocytes. To further examine the role of CD4+ T cells in the immune response to influenza infection, we have generated influenza virus-specific CD4+ T cell clones from influenza-primed BALB/c mice with differential cytokine secretion profiles that are defined as T helper type 1 (Th1) clones by the production of interleukin 2 (IL-2) and interferon gamma (IFN-gamma), or as Th2 clones by the production of IL-4, IL-5, and IL-10. Our studies have revealed that Th1 clones are cytolytic in vitro and protective against lethal challenge with virus in vivo, whereas Th2 clones are noncytolytic and not protective. Upon further evaluation of these clonal populations we have shown that not only are the Th2 clones nonprotective, but that pulmonary pathology is exacerbated as compared with control mice as evidenced by delayed viral clearance and massive pulmonary eosinophilia. These data suggest that virus-specific CD4+ T cells of the Th2 subset may not play a primary role in virus clearance and recovery and may lead to immune mediated potentiation of injury.

Increased Expression of PD-1 on CD4+ T Cells from Patients with Chronic Lymphocytic Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4154-4154
Author(s):  
Mary M Sartor ◽  
David J Gottlieb
Keyword(s):  
T Cells ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Nk Cells ◽  
Cd4 T Cells ◽  
Mononuclear Cells ◽  
Lymphocytic Leukemia ◽  
Effector Memory ◽  
Cd4 Cells ◽  
Normal Peripheral Blood

Abstract Although the predominant finding in patients with chronic lymphocytic leukemia (CLL) is an expansion of monoclonal B lymphocytes, a polyclonal expansion of T cells co-exists in CLL patients. Allogenic stem cell transplants for CLL suggest that a significant graft versus leukaemia effect mediated through recognition of minor MHC or leukaemia specific antigens can be achieved. Since it appears that the immune system and probably T cells recognise CLL cells, it is possible that one or more T cell defects might contribute to the initiation or maintenance of a clone of CLL lymphocytes. PD-1 is a coinhibitory molecule that is expressed on T cells in patients with chronic viral infections. It has been suggested that PD-1 expression might be a marker of cell exhaustion due to antigenic overstimulation. We examined the expression of PD-1 and its naturally occurring ligands PD-L1 and PD-L2 on both B and T cells in patients with CLL and compared this with expression on normal peripheral blood mononuclear cells. We found that PD-1 was expressed on over 10% of CD4+ T cells in 7 of 9 cases of CLL (mean 22±16%) but not on CD4+ T cells in any of 9 normal donors (mean 0±0%), p=0.0009. There was no difference in PD-1 expression on CD8+ or CD14+ PBMCs from CLL patients and normal donors (for CD8+ 24±21% and 19±16% for CLL and normals; for CD14+ 58±16% and 71±31% for CLL and normals). More than 10% of CD5+/19+ CLL cells expressed PD-1 in 7 of 10 cases (mean 18±18%) while more than 10% of normal B cells from 6 of 7 donors also expressed PD-1 (mean 49±30%). We examined the expression of PD-1 on naïve, central memory, effector memory and terminally differentiated subsets of CD4+ cells (CD62L+CD45RA+, CD62L+CD45RA−, CD62L−CD45RA− and CD62L−CD45RA+ respectively) from CLL patients and normal donors. The expression of PD-1 was higher on CD4+ cells from CLL patients in all subsets. The effect was most prominent in the effector memory subset (mean 54±4% for CLL patients versus 26±17% for normal donors, p=0.02). We looked for expression of PD-L1 and PD-L2 on T cells, B cells, monocytes and NK cells from CLL patients and normal donors. PD-L1 was only expressed on monocytes (mean 30±23%) and NK cells (mean 14±19%) from CLL patients and on monocytes from normal donors (mean 35±26%). There was no expression of PD-L2 on any cell type in either CLL patients or normal donors. We conclude that there is increased expression of the co-inhibitory molecule PD-1 on CD4+ T cells in patients with CLL. Ligation of PD-1 by PD-L1 expressed on monocytes or NK cells could inhibit immune responses to tumor and infectious antigens leading to persistence of clonally expanded cells and predisposition to opportunistic pathogens.

Selective Clearance of Chronic Lymphocytic Leukemia Cells in Vivo Following Treatment with UC99961, an Anti-ROR1 Monoclonal Antibody

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3886-3886
Author(s):  
Eva Hellqvist ◽  
Christina C.N. Wu ◽  
George F. Widhopf ◽  
Alice Shih ◽  
Rommel Tawatao ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
T Cells ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Cord Blood ◽  
Peritoneal Lavage ◽  
Lymphocytic Leukemia ◽  
Leukemia Cells ◽  
Human Cord Blood

Abstract Abstract 3886 ROR1 is a receptor-tyrosine kinase like protein expressed on the surface of chronic lymphocytic leukemia (CLL) B cells, but not on normal mature B cells, suggesting that it may be a promising therapeutic target. We have generated a chimeric monoclonal antibody (mAb), UC99961, which binds to an intradomain epitope of human ROR1 (hROR1). UC99961 binds the same epitope as the murine anti-hROR1 mAb, UC D10–001, which has direct cytotoxic effects on hROR1 positive CLL cells. In this study we investigated the in-vivo anti-leukemic activity and tolerability of UC99961 on ROR1+ primary patient CLL cells and human cord-blood-derived B cells and T cells, respectively. For these studies, immunodeficient RAG2−/−γc−/− neonatal mice were reconstituted with a human immune system by intrahepatic xenotransplantation of 1×105 CD34+ human cord blood progenitor cells. Eight to ten weeks post transplantation, cord blood engraftment was verified by peripheral blood screening, at which point the mice received an intraperitoneal transplantation of 2×107 primary patient ROR1+ CLL cells. Twenty-four hours after CLL transplantation, five animals per group were each treated with a single intraperitoneal injection (10mg/kg) of UC99961, UC D10–001, or control IgG. Seven days following mAb treatment, the animals were sacrificed and marrow, spleen, thymus, and peritoneal lavage samples were collected and analyzed by flow cytometry for CLL cells, as well as normal cord-blood-derived B cells and T cells. To confirm mAb administration according to the study design, serial residual ROR1 plasma antibody levels were determined by ELISA. Results from three consecutive experiments using leukemia cells from two different patients showed that the vast majority of CLL B cells remained in the peritoneal cavity of the animals and did not migrate to other hematopoietic organs. Both anti-hROR1 mAbs UC99961 and UC D10–001 significantly reduced the average number of harvested CLL cells in the peritoneal lavage compared to control IgG (99% and 71% reduction respectively), while cord-blood-derived T cells (CD45+3+) in thymus remained unaffected by the mAb treatment. For the majority of cord-blood-derived B cells in marrow and spleen, no significant reduction could be observed after UC99961 or UC D10–001 mAb treatment. A small CD19+ROR1+CD34− cord-blood-derived B cell population was identified in marrow and spleen that was reduced after UC99961 and UC D10–001 mAb treatment. This study demonstrates that the anti-human ROR1 specific mAbs have in vivo anti-leukemic activity with minimal impact on human cord-blood-derived B cells and T cells. From these results, UC99961 appears to be an excellent candidate antibody for future clinical studies for patients with CLL. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Induction of in vitro differentiation and immunoglobulin synthesis of human leukemic B lymphocytes.

1978 ◽  
Vol 148 (6) ◽  
pp. 1570-1578 ◽  
Author(s):  
S M Fu ◽  
N Chiorazzi ◽  
H G Kunkel ◽  
J P Halper ◽  
S R Harris
Keyword(s):  
T Cells ◽  
B Cells ◽  
Plasma Cells ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Pokeweed Mitogen ◽  
In Vitro Differentiation ◽  
Immunoglobulin Synthesis

Successful induction of in vitro differentiation and immunoglobulin synthesis of the leukemic lymphocytes was carried out in two cases of chronic lymphocytic leukemia. Few plasma cells and little specific Ig secretion were detected in the cultures of isolated leukemic B cells in either the presence or the absence of autologous T cells. Up to 30% of the leukemic B cells matured to plasma cells, and a 32-fold increase in specific Ig synthesis was observed when T cells from normal individuals were added to the cultures of these leukemic B cells. In one of the two cases, autologous T cells were able to induce greater than 50% of the leukemic B cells to differentiate further to plasma cells in the presence of pokeweed mitogen. This markedly accelerated in vitro differentiation was only achieved with leukemic cells from cases in which there was evidence of slight differentiation in vivo. No evidence could be obtained for excessive suppressor T cells in these patients. However, a T-cell defect in the generation of allogeneic effect helper factors was identified. This defect may be responsible for the reduced rate of leukemic maturation in vivo.

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