Proposal For a Novel Scoring System For The Diagnosis Of CLL

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4150-4150 ◽  
Author(s):  
Thomas Köhnke ◽  
Veronika K Wittmann ◽  
Daniela Sauter ◽  
Veit Bücklein ◽  
Zlatana Pasalic ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Differential Diagnosis ◽  
B Cells ◽  
B Cell ◽  
Sensitivity And Specificity ◽  
Validation Cohort ◽  
Diagnostic Value ◽  
Internal Validation ◽  
Expression Intensity ◽  
Higher Sensitivity

Abstract Background Immunophenotyping is essential for the diagnosis of chronic lymphocytic leukemia (CLL). The scoring proposed in the modified Matutes score has been the basis of diagnosis for the past 15 years and is defined by strong expression of CD5 and CD23, low or absent expression of CD79b, sIgM and FMC7. However, some markers within the current score such as sIgM display a high variability in staining patterns and thus the interpretation of expression intensity is not easily reproducible. Furthermore, the newly identified marker CD200 is not included in the current score in spite of its highly informative value in the differential diagnosis of B-cell disorders. In the study presented here we aimed to improve the current score through the addition of highly informative markers such as CD200 and the omission of sIgM as a less informative, error-prone marker. Methods Between February 2011 and May 2013, peripheral blood or bone marrow aspirates of patients with suspected B-cell lymphoproliferative disorders were subjected to evaluation by flow cytometry. Immunophenotyping was performed using a Navios flow cytometer (Beckman Coulter) and samples were stained by monoclonal antibodies targeting the antigens CD45, CD19, CD5, CD10, CD23, CD79b, CD200, FMC7, sIgM, kappa and lambda. Corresponding isotype controls were used. The modified Matutes score was calculated as described previously (Moreau et al., Am J Clin Pathol 1997) with positivity defined as ≥20% positive cells. Mean Fluorescence Intensity (MFI) ratio (MFI sample/MFI isotype) was calculated as a measure of expression intensity. For our new score, optimized cut-offs for positivity vs. negativity (CD5, CD23, CD200, FMC7) and low or absent expression (CD79b) as well as sensitivity and specificity were calculated by receiver operating characteristics (ROC). The final clinical diagnosis was defined as the diagnosis established by the treating physician taking into account clinical symptoms as well as all results from diagnostic procedures, including cytomorphology, flow cytometry, cytogenetics, molecular genetics and immunohistochemistry, if available. In order to perform an internal validation of our proposed score, we divided the patient cohort into an exploratory and a validation cohort by a 2:1 ratio based on the date of receipt of the samples. Result Flow cytometry data of 371 patients with B-cell disorders were available for analysis. 247 patients were assigned to the exploratory cohort and 124 patients were assigned to the validation cohort. 84.2% and 82.1% of patients, respectively, were diagnosed with CLL. In the exploratory cohort, sIgM-expression intensity on CD19+ B-cells (as measured by MFI ratio) was significantly lower in CLL versus non-CLL cases (p=0.001). However, low or absent sIgM-expression displayed poor specificity in distinguishing CLL from non-CLL cases (51,3%; sensitivity 83,7%). Absent or low CD79b-expression on CD19+ B-cells showed a higher sensitivity and specificity (94.2% and 71.8%, respectively). Positivity for CD200 as well as lack of FMC7-expression showed high diagnostic value (sensitivity and specificity all above 80%). Interestingly, positivity for CD5 on CD19+ B-cells did not have a strong diagnostic value (sensitivity and specificity 69.7% and 76.9%, respectively), but double positivity for CD5 and CD23 on CD19+ B-cells showed higher sensitivity and specificity (79.8% and 87.2%, respectively). Therefore, CD200+, CD23+/CD5+, FMC7- and low or absent CD79b on CD19+ B-cells were included in a new diagnostic score. The resulting score showed comparable sensitivity (97.1% for our score versus 98.6% for the Matutes score, McNemar’s test p=0.38), but markedly increased specificity (87.2% versus 53.8%, p<0.001). These results were confirmed in the internal validation cohort (sensitivity 97.0% versus 100%, p=N/A; specificity 86.4% versus 59.1%, p=0.03). Conclusion The data support the use of the improved score for the differential diagnosis of CLL. This novel scoring system exhibits significantly higher specificity while maintaining very high sensitivity and might therefore contribute to less false positive results. Finally, the surface markers contained in the novel score show more consistent staining patterns, which might further improve reproducibility. External validation of the proposed score will be pursued. Disclosures: No relevant conflicts of interest to declare.

Multiparameter Flow Cytometry (MFC) for Identification of the Waldenström's Clone in IgM MGUS and Waldenstrom's Macroglobulinemia (WM): New Criteria for Differential Diagnosis and Risk Stratification

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 936-936
Author(s):  
Bruno Paiva ◽  
Maria-Carmen Montes ◽  
Ramón García-Sanz ◽  
Jennifer Alonso ◽  
Natalia de las Heras ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Differential Diagnosis ◽  
B Cells ◽  
B Cell ◽  
Light Chain ◽  
Conflicts Of Interest ◽  
Phenotypic Characterization ◽  
International Prognostic Scoring System ◽  
Multiparameter Flow Cytometry ◽  
Risk Of Progression

Abstract Abstract 936 Demonstration of bone marrow (BM) infiltration by lymphoplasmacytic lymphoma is essential to the diagnosis of WM, and a trephine biopsy is considered mandatory for this assessment. Multiparameter flow cytometry (MFC) has demonstrated its clinical relevance in MGUS and myeloma; however, immunophenotypic studies on IgM monoclonal gammopathies are scanty, and focus only in patients with WM. Herein, MFC immunophenotyping was performed on BM samples from 244 patients, including 67 IgM MGUS, 77 smoldering, and 100 symptomatic WM newly diagnosed patients according to the Second International Workshop. A four color panel that systematically allowed the identification of B cells and plasma cells (PC), and their phenotypic characterization for a total of 24 antigens was used. We first analyzed the percentage of B cells and PC in BM and the percentage of light chain restricted cells in both compartments. Our results show a progressive increment of B cells from IgM MGUS to smoldering and symptomatic WM (medians of 2%, 9% and 12%; P<.001), as well of light chain restricted B cells (75%, 96% and 99%; P<.001). In contrast, no differences were found for the percentage of PC (median of 0.3%), but light chain restricted PC progressively increased from IgM MGUS to smoldering and symptomatic WM (70%, 85% and 97%; P<.001). Accordingly, only 1% of IgM MGUS patients showed >10% B cells, in contrast to 34% and 55% of smoldering and symptomatic WM (P<.001). Likewise, only 1% of IgM MGUS patients showed 100% light chain restricted B cells, in contrast to 19% and 40% of smoldering and symptomatic WM (P<.001); similar results being also found using a cutoff of 100% light chain restricted PC. Subsequently, we explored whether the percentages of BM and light chain restricted B cells and PC could predict time to progression (TTP) from smoldering into symptomatic WM, as well as overall survival (OS) in symptomatic WM. In smoldering WM, B cells (>10% vs ≤10%: median TTP of 47m vs 145m; P=.016) and light chain restricted B cells (100% vs <100%: 26m vs 145m; P<.001) but not PC, predicted risk of progression. On the multivariate analysis that included serum M-spike (±3g/dL), BM infiltration (±50% lymphoplasmacytic cells), BM B-cells and light chain restricted B cells (by MFC), only the later retained independent prognostic value (HR: 19.8, P=.001). Upon analyzing factors influencing survival in symptomatic WM patients, cases with >10% B cells showed a trend for inferior OS (P=.080), and significant differences emerged when comparing patients with 100% vs <100% light chain restricted B cells (median OS 44m vs 78m; P=.001). The later marker was independent (HR: 2.6; P=.004) of the International Prognostic Scoring System (HR: 2.2; P=.006). Focusing on the antigenic profiles of B cells and PC, we noted that within the B-cell compartment there was a progressive increment of CD22dim (69%, 92% and 88%; P<.001), CD25+ (61%, 88% and 90%; P<.001) and sIgM+ (88%, 95% and 97%; P=.002) B cells from IgM MGUS to smoldering and symptomatic WM. This underlies that the accumulating light chain restricted clonal B cells show a characteristic Waldenstrom's phenotype (CD22dim/CD25+/IgM+). Of note, a bimodal (from - to +) expression for the B cell memory marker CD27 was found in >50% of WM patients, which raises the possibility that the WM clone may arise, at least in some cases, before antigenic stimulation; subsequent maturation of the clone into PC would explain the typical presence of somatic hypermutations. On the other hand, B-cells from IgM MGUS and WM patients were negative in ≥90% of cases for CD5, CD10, CD11c and CD103, which can be useful to differentiate between WM and other B-NHL. Finally, the antigenic profile of PC in IgM MGUS and WM was similar to that of normal PC, and different from myeloma PC by consistently showing a CD27+ and CD56- phenotype, in addition to sIgM+ expression in ≥87% of all cases. Similarly to B-cells, we also noted that within the PC compartment there was a progressive increment of CD19+, CD45+ and sIgM+ CD20+ PC from IgM MGUS to smoldering and symptomatic WM. This underlies that this transition is asssociated with an accumulation of light chain restricted clonal PC displaying an immature/plasmablastic phenotype. In summary, our results highlight the potential value of MFC immunophenotyping for the characterization of the Waldenström's clone, as well as for the differential diagnosis, risk of progression and survival in WM. Disclosures: No relevant conflicts of interest to declare.

Junctional Adhesion Molecule C (JAM-C) Constitutes a New Marker for the Differential Diagnosis of B Cell Lymphomas.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3940-3940
Author(s):  
Thomas Matthes ◽  
Christiane Ody ◽  
Beat Imhof ◽  
Carmen Donate ◽  
Dominique Cossali ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Differential Diagnosis ◽  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Marginal Zone ◽  
Plasma Cells ◽  
B Cell Differentiation ◽  
B Cell Lymphomas

Abstract Abstract 3940 Poster Board III-876 Introduction Differentiation of naïve B cells into plasma cells or memory cells occurs in the germinal centres (GC) of lymph follicles or alternatively in the marginal zone via a GC- and T cell independent pathway. It is currently assumed that B cell lymphomas correspond to normal B cell differentiation stages, but the precise correlation of several B cell lymphomas to these two pathways remains controversial. We have previously shown that junctional adhesion molecule C (JAM-C) originally identified at the cell-cell border of endothelial cells, constitutes also a marker of B lymphocytes with a tightly regulated expression during B cell differentiation: immature B cells, GC-B cells and plasma cells stain negatively, whereas mature, memory and marginal zone derived B cells stain strongly positive. Here we test the expression of JAM-C on a series of patients with B cell lymphomas. Methods B lymphocytes from the peripheral blood of 158 untreated patients were analyzed using flow cytometry with standard antibody panels (CD5, CD10, CD11c, CD22, CD23, CD25, CD38, CD103, FMC7, sIg). Diagnosis of a B cell lymphoma was established according to WHO guidelines, using additionally RT-PCR, karyotyping, or FISH, if necessary. Expression of JAM-C was studied by flow cytometry with a polyclonal antibody obtained from a rabbit immunized with the soluble JAM-C molecule. Results MCL, HCL and MZBL with a supposed origin in the marginal zone stained mostly positive, whereas CLL and FL with a supposed origin in the germinal centre showed mostly a negative staining. No correlation was found in CLL between JAM-C expression and staining for ZAP70 or CD38. In 12 cases routine work-up was not able to precisely establish a diagnosis of CLL or MZBL, and CLL or MCL. In these cases the presence of JAM-C was considered a strong argument against a GC-origin of the malignant B cells. Addition of JAM-C to antibodies used in the Matutes score increased the sensitivity and specificity of this score for the diagnosis of CLL. Furthermore, it may help differentiating MZBL from LPL which otherwise display overlapping immunophenotypes. Conclusion JAM-C constitutes a new diagnostic marker for the differential diagnosis of B cell lymphomas, and is particularly useful for the distinction between CLL and LPL (negative staining) on the one hand and mantle cell and marginal zone B cell lymphomas (positive staining) on the other hand. Disclosures: No relevant conflicts of interest to declare.

scholarly journals OP0186 CHANGES IN CIRCULATING B CELL LEVELS AND IMMUNOPHENOTYPE ARE ASSOCIATED WITH DEVELOPMENT OF ARTHRITIS FOLLOWING TREATMENT WITH CHECKPOINT INHIBITORS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 112.2-113
Author(s):  
M. Gatto ◽  
S. Bjursten ◽  
C. Jonell ◽  
C. Jonsson ◽  
S. Mcgrath ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
Adverse Events ◽  
B Cell ◽  
Mononuclear Cells ◽  
Checkpoint Inhibitors ◽  
Therapy Monitoring ◽  
Cell Subset ◽  
Peripheral Blood Mononuclear ◽  
Transitional B Cells

Background:Inflammatory arthritis (IA) is frequent among rheumatic side effects induced by checkpoint inhibitor (CPI) therapy for metastatic malignancies1. While T cells are likely to sustain the inflammatory process2, fewer data are available concerning the role of B cells3.Objectives:To investigate the phenotype of circulating B cells in patients who develop CPI-induced IA (CPI-IA) and to compare it with features of B cells in patients not developing immune-related adverse events (irAE) upon CPI treatment.Methods:B cell subsets at baseline (before CPI initiation) and during CPI treatment were analyzed in CPI-IA patients and in patients receiving CPI but who did not develop irAE (non-irAE). Peripheral blood mononuclear cells (PBMC) were analyzed by flow cytometry and B cells were identified as CD19+ and divided into naïve (CD27-IgD+), memory (CD27+IgD+/-), double negative (CD27-IgD-) and transitional (CD10+CD24+CD38+/hi) B cells. Levels of CD21, an activation marker on transitional B cells, were also analyzed. Non-parametric tests were used for analysis of differences between groups.Results:Six CPI-IA and 7 non-irAE patients matched for age, gender and CPI treatment were included, who had received CPI treatment due to metastatic melanoma. Flow cytometry revealed a significant increase of circulating B cells (p=0.002) (Figure 1A) and especially of transitional B cells in CPI-IA patients vs. non-irAE (median %, range: 7.8 (4.5-11.4) vs. 3.2 (1.6-4.3),p=0.007) (Figure 1B), while no remarkable changes were seen across other subsets. Transitional B cell levels significantly decreased from active to quiescent CPI-IA in all patients (p=0.008). In two CPI-IA patients for whom baseline sampling was available, the increase of transitional levels occurred early after CPI treatment and before CPI-IA onset. Levels of expression of CD21 on transitional B cells were increased in CPI-IA vs. non-irAE (p=0.01).Conclusion:Transitional B cells are expanded in CPI-IA patients and seem to increase early after start of CPI therapy. Monitoring this B cell subset might lead to closer follow-up and earlier diagnosis of CPI-IA.References:[1]Ramos-Casals M, Brahmer JR, Callahan MK, et al. Immune-related adverse events of checkpoint inhibitors. Nat Rev Dis Primers 2020;6:38[2]Murray-Brown W, Wilsdon TD, Weedon H, et al. Nivolumab-induced synovitis is characterized by florid T cell infiltration and rapid resolution with synovial biopsy-guided therapy. J Immunother Cancer 2020;8:e000281[3]Das R, Bar N, Ferreira M, et al. Early B cell changes predict autoimmunity following combination immune checkpoint blockade. J Clin Invest. 2018;128:715-2Disclosure of Interests:None declared

scholarly journals Expert-independent classification of mature B-cell neoplasms using standardized flow cytometry: a multicentric study

2021 ◽  
Author(s):  
Sebastian Böttcher ◽  
Robby Engelmann ◽  
Georgiana Grigore ◽  
Paula Carolina Fernandez ◽  
Joana Caetano ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Differential Diagnosis ◽  
Follicular Lymphoma ◽  
B Cell ◽  
Diagnostic Algorithm ◽  
Lymphocytic Leukemia ◽  
B Cell Lymphomas ◽  
Multicentric Study ◽  
Predictive Values ◽  
Large B Cell

Reproducible expert-independent flow-cytometric criteria for the differential diagnoses between mature B-cell neoplasms are lacking. We developed an algorithm-driven classification for these lymphomas by flow cytometry and compared it to the WHO gold standard diagnosis. Overall, 662 samples from 662 patients representing nine disease categories were analyzed at 9 laboratories using the previously published EuroFlow 5-tube-8-color B-cell chronic lymphoproliferative disease antibody panel. Expression levels of all 26 markers from the panel were plotted by B-cell entity to construct a univariate, fully standardized diagnostic reference library. For multivariate data analysis we subsequently utilized Canonical Correlation Analysis of 176 training cases to project the multi-dimensional space of all 26 immunophenotypic parameters into 36 two-dimensional plots for each possible pair-wise differential diagnosis. Diagnostic boundaries were fitted according to the distribution of the immunophenotypes of a given differential diagnosis. A diagnostic algorithm based on these projections was developed and subsequently validated using 486 independent cases. Negative predictive values exceeding 92.1% were observed for all disease categories except for follicular lymphoma. Particularly high positive predictive values were returned in chronic lymphocytic leukemia (99.1%), hairy cell leukemia (97.2%), follicular lymphoma (97.2%) and mantle cell lymphoma (95.4%). Burkitt and CD10+ diffuse large B-cell lymphomas were difficult to distinguish by the algorithm. A similar ambiguity was observed between marginal zone, lymphoplasmacytic, and CD10- diffuse large B-cell lymphomas. The specificity of the approach exceeded 98% for all entities. The univariate immunophenotypic library and the multivariate expert-independent diagnostic algorithm might contribute to increased reproducibility of future diagnostics in mature B-cell neoplasms.

The Loss of Kdm6a in B-Cell Development Causes Germinal Center Hyperplasia and Impedes the B-Cell Immune Response in a Specific Manner

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 5-5
Author(s):  
Ling Tian ◽  
Monique Chavez ◽  
Lukas D Wartman
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Cell Development ◽  
Young Female ◽  
B Cell Development ◽  
Cell Immune Response ◽  
Germinal Center Hyperplasia

Putative loss-of-function mutations in KDM6A, an X-linked H3K27 demethylase, occur recurrently in B-cell malignancies, including B-cell non-Hodgkin lymphoma. How the KDM6A in normal B cell development and function, as well as the mechanism(s) by which its loss contributes lymphomagenesis has not been defined. To address this issue, we generated a conditional knockout mouse of the Kdm6a gene (with LoxP sites flanking the 3rd exon) and crossed these mice with Vav1-Cre transgenic mice to selectively inactivate Kdm6a in hematopoietic stem/progenitor cells. Our previous data have shown young Kdm6a-null mice have a myeloid skewing in the bone marrow, spleen and peripheral blood. These changes became more pronounced with age and were specific to the female, homozygous Kdm6a knockout mice. Early B-cell development is also altered in female Kdm6a-null mice. Flow cytometry showed a decrease in multipotent progenitor cells (MPPs) with a decrease in both common lymphoid progenitors (CLPs) and B cell-biased lymphoid progenitors (BLPs) in young, female Kdm6a-null mice bone marrow. B-cell progenitor analysis (Hardy profiles) showed an increase in Fraction A with a concomitant decrease in Fraction B/C and Fraction D. The GC B-cells are thought to be the cell-of-origin of diffuse large B-cell lymphoma (DLBCL). To determine if the loss of Kmd6a could impact the mature B cells undergo germinal center (GC) reaction, we immunized the young, female Kdm6a-null mcie and wildtype littermates with T cell-dependent antigen sheep red blood cell (SRBC). Mice were scrificed 14 days after immunization, spleen cells were examined by flow cytometry. As expected, we observed a significant increase in the percentage of GC B cells (B220+GL7+CD95+) from female Kdm6a-null mice compared to control mice. We also observed differences in the percentage of other B-cell subsets between these mice, including an increase in plasma cells (B220-CD138+) and memory B cells (B220+CD19+CD27+), concomitant with an increase trend towards the elevated marginal zone B cells (B220+CD23loCD21+) and transitional B cells (B220+CD23-CD21-). In contrast, there was a decrease in the follicular zone B cells (B220+CD23-CD21-) and plasmablast (B220+CD138+). To analyze the levels of SRBC-specific Abs from immunized mice, serum was collected from blood at day 14. A flow cytometry-based assay was performed to detect the fluorescent-labeled SRBC-specfic Abs for immunoglobulin. Results showed that the abundance of non-class-switched anti-SRBC IgM level was significantly increased in female Kdm6a-null mice serum compared with control mice. In contrast, these mice had significantly decreased anti-SRBC IgA, IgG, IgG1, IgG3 and IgE levels indicating a isotype class switch defect. The aberrant GC phenotype induced by SRBC indeicated that kdm6a loss results in expansion of GC B cells, which subsequently enhances the plasma cell generation. This finding prompted us to investigate if the Kdm6a impairs the immunoglobulin affinity maturation. Therefore, we analyzed the ability of female Kdm6a-null mice and wildtype littermates to generate specific Abs against another T cell-dependent antigen NP-Chicken Gamma Globulin (NP-CGG). Mice were immunized with NP-CGG (29) and serum were collected weekly up to 8 weeks total. ELISA analysis of serum revealed that NP-specfic total Ig level were similar for both groups of mice over time. However, consistent with the SRBC immunization results, we did observed a sinificant reduction in the titers of NP-specific IgA and IgG1 Abs in female Kdm6a-null mice compared with control mice at each time point, while these mice had a sinificant increase in NP-specific IgM Abs, which indicating the loss of Kdm6a disrupts the balance between non-class-switched and class-switched NP-specific Abs isotypes (Figure 1A-D). Likewise, we also observed an increase in the percentage of GC B cells and plasma cells 8 weeks after NP-CGG immunization by flow cytometry. Again, our findings indicate the loss of Kdm6a causes germinal center hyperplasia, enhances plasma cell differentiation, and likely impairs class switch recombination (CSR). Taken together, our data shows that Kdm6a plays an important, but complex, role in B-cell transiting in the GC reaction and that loss of Kdm6a causes germinal center hyperplasia and impedes the B-cell immune response in a specific manner that may contribute to infection and B-cell malignancies. Disclosures Wartman: Novartis: Consultancy; Incyte: Consultancy.

A New Vaccine Paradigm To Break Tolerance with Potential Applications for the Immunotherapy of B Cell Lymphoma.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1411-1411
Author(s):  
Ronald P. Taylor ◽  
Emily C. Whipple ◽  
Margaret A. Lindorfer ◽  
Andrew H. Ditto ◽  
Ryan S. Shanahan
Keyword(s):  
Flow Cytometry ◽  
Immune Response ◽  
B Cells ◽  
B Cell ◽  
Humoral Immune Response ◽  
Critical Role ◽  
B Cell Lymphoma ◽  
Breakdown Product ◽  
Humoral Immune ◽  
Mouse Igg2a

Abstract Complement (C) plays a critical role in the immune response by opsonizing immune complexes (IC) and thymus-independent type 2 antigens with C3 breakdown product C3dg. We investigated the in vivo fate and handling in mice of anti-CR1/CR2 mAb 7G6. We used this rat IgG mAb as a surrogate for C3dg-opsonized IC; mAb 7G6 binds to CR1/CR2 with high affinity, blocks C3dg binding and saturates mouse B cell CR2 at inputs of only 2 ug. RIA, flow cytometry, and fluorescence immunohistochemistry were used to examine the disposition of 0.5–2 ug quantities of mAb 7G6 infused i.v. in mice. The mAb binds to circulating B cells and in the spleen binds preferentially to marginal zone (MZ) B cells. However, within 24 h MZ B cells relocate and transfer the mAb to regions rich in follicular dendritic cells (FDC). Localization of intact antigen to FDC should induce a substantial immune response, and therefore we immunized mice and monkeys i.v. with low doses (1–20 ug/kg) of prototype antigens constructed with anti-CR1/2 mAb 7G6 or anti-CR2 mAb HB135, respectively. We observed a strong immune response characterized by early development of IgG antibodies and long-lasting immunity extending out to at least one year. We applied our immunization paradigm to mouse IgG idiotypes, based on i.v. infusion of mouse IgG2a mAbs which were cross-linked with mAb 7G6. The purpose of these experiments was to determine if tolerance can be broken in order to develop a more powerful vaccine strategy to induce a cytotoxic humoral immune response to malignant B cells based on targeting the idiotype of immunoglobulin molecules expressed on their surfaces. I.V. immunization with the constructs indeed generated a mouse IgG1 immune response to two different mouse IgG2a mAbs, as demonstrated by ELISA. The immune response was idiotype specific, but some anti-isotype antibodies were also detected. Moreover, sera from immunized mice immunoprecipitated the specific radiolabeled mouse mAbs in the presence of 7.5% polyethylene glycol. This humoral immune response was also demonstrable in flow cytometry assays in which IgG1 in sera of immunized mice bound to erythrocytes opsonized with bispecific mAb constructs consisting of the IgG2a mAb crosslinked with an anti-CR1 mAb. The present approach, based on coupling the targeted immunoglobulin to an anti-CR2 mAb for delivery to FDC, may lead to a more effective immunotherapeutic vaccine compared to methods currently in clinical trials which require use of glutaraldehyde to effect crosslinking of the targeted immunoglobulin to KLH.

Tumor Cells Resistant to Alemtuzumab Complement Mediated Cytotoxicity in Patients with High Risk Previously Untreated Early Stage CLL: A Possible Mechanism of Treatment Failure.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2973-2973
Author(s):  
Clive S. Zent ◽  
Nancy D. Bone ◽  
Susan M. Geyer ◽  
Neil E. Kay
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
High Risk ◽  
B Cell ◽  
Cell Clone ◽  
Early Stage ◽  
Cell Membrane Permeability ◽  
Viable Cells ◽  
The Impact

Abstract The monoclonal antibodies (MoAb) alemtuzumab and rituximab have proven efficacy in the treatment of CLL. In addition, alemtuzumab is effective in patients with defective p53 function responding poorly to purine analogue therapy. The action of both MoAb is not completely understood. Proposed mechanisms include complement dependent cytotoxicity (CDC), antibody dependent cellular cytotoxicity (ADCC), and direct induction of apoptosis of CLL B cells. We have done correlative studies on CLL B cells from patients enrolled in a trial of alemtuzumab and rituximab in “high risk” early stage previously untreated CLL to determine: 1. Role of apoptosis induction and CDC in each MoAb and 2. If the addition of rituximab to alemtuzumab increases their in vitro cytotoxicity. Patients and Methods: Patients with early stage, previously untreated, high risk CLL are treated with subcutaneous alemtuzumab (dose escalation over 3 days then 30 mg Mon-Wed-Fri for 4 weeks) and rituximab (375 mg/m2/dose weekly from day 8 x 4 doses). High risk disease was defined as one or more of the following features of the CLL B cell clone: (1) 17p13−; (2) 11q22−; (3) unmutated IgVH (&lt; 2%) and either CD38+ or ZAP-70+. Blood B lymphocytes collected prior to the start of therapy were tested for response to MoAb in vitro. Cells were cultured at 2 x 106/ml in AIM-V medium using standard conditions. Alemtuzumab and rituximab were used at 20 μg/ml and complement as 10% of 40 CH50 units/ml human serum. The impact of the MoAb was measured by counting viable cells (trypan blue negative) and measuring early apoptosis (annexin V) and cell death (cell membrane permeability to propidium iodide) using flow cytometry at 1 hour, and then daily for 3 days. Results: Treatment caused rapid resolution of lymphocytosis in all 7 patients and 3 patients were negative for circulating CLL cells using a highly sensitive 3 color flow cytometry (CD5+/CD19+/CD79b-) after therapy. All patients had a clinical response (2 CR, 5 PR). Alemtuzumab and complement were rapidly cytotoxic to most CLL cells. Mean cell viability was 39% (sd: 8%) after 1 hour of incubation. Cytotoxicity was similar in all samples irrespective of FISH defects, IgVH mutation status, and in vitro resistance to F-ara-A (n = 3). Alemtuzumab was inactive in the absence of complement for all samples. Rituximab alone and together with complement did not induce cytotoxicity or apoptosis. However, the addition of rituximab to alemtuzumab and complement did increase CDC where the number of viable cells was significantly lower at 1, 24, 48, and 72 hours incubation (p = 0.075, 0.047, 0.031, 0.027, respectively, for pairwise comparisons). CLL cells surviving alemtuzumab CDC subsequently had a lower level of apoptosis than control cells, implying a selection for resistant cells. Alemtuzumab CDC on this residual population was not increased at higher concentrations of alemtuzumab or complement. This mechanism of CDC resistance is currently under investigation. Conclusion: These data suggest that alemtuzumab CDC is an important mechanism of action in patients with CLL. However, alemtuzumab CDC kills only about 61% of CLL cells in vitro, and the surviving cells are more resistant to spontaneous apoptosis. This suggests that cells that survive alemtuzimab CDC contribute to disease progression or relapse. We intend to elucidate the mechanism of this resistance using our in vitro model with the hope that treatment strategies can be deployed to remove this residual CLL B cell clone.

Expression of NTB-A in Normal Tissue, Non-Hodgkin Lymphomas and Investigation of Its Potential Therapeutic Impact for Chronic Lymphocytic Leukemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4741-4741
Author(s):  
Xiaoxian Zhao ◽  
Wouter Korver ◽  
Nichole Prescott ◽  
Arie Abo ◽  
Eric Hsi
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
B Cell ◽  
Progenitor Cells ◽  
Blood Cells ◽  
Cell Lymphoma ◽  
White Blood Cells ◽  
B Cell Lymphoma ◽  
Hematologic Malignancies ◽  
Normal Tissues

Abstract Introduction: Expressed on T, B, NK cells and neutrophils, NTB-A belongs to the signaling lymphocytic activation molecule (SLAM) family of immune receptors. It was reported recently that cross-linking of NTB-A induces T cell activation and Ly108 (the presumed mouse orthologue of NTB-A) controls the production of reactive oxygen species in neutrophils. To date, little is known about its expression at the protein level in normal tissues, or in hematologic malignancies. Methods: We have generated monoclonal antibodies (mAbs) to NTB-A and used tissue microarrays (TMAs) to screen normal tissues and lymphomas. Western blotting and flow cytometry were used for confirmation of selected entities. Complement dependent cytotoxicity (CDC) assays were performed using the CellTiter-Glo Luminescent Cell Viability Assay kit (Promega). Results: NTB-A was not detected in normal tissues including heart, liver, breast, kidney, brain, lung, uterus, small intestine, skin, prostate, pancreas, ovary, bladder, testis and stomach (5/5 negative cases for all above tissues) by IHC. Expression was observed in lymphocytes of normal tonsil and spleen. In lymphomas, we found NTB-A expression in diffuse large B-cell lymphoma (DLBL), follicular lymphoma, small lymphocytic lymphoma (SLL), mantle cell lymphoma and Burkitt lymphoma. Western blotting and flow cytometry of B-cell lymphoma cell lines DOHH2 (DLBL) and Raji (Burkitt) confirmed NTB-A expression in these lines. Myeloma cell lines were negative for expression. Flow cytometry of normal blood cells showed expression of NTB-A in B-cells, T-cells and NK cells (95.5 ± 6.7%, 62.6 ± 29.5% and 72.7 ± 26.5%, respectively) but not in CD66+ granulocytes. Furthermore, CD34+ progenitor cells from bone marrow were negative. Because of the expression in SLL, we focused on chronic lymphocytic leykemia (CLL) cells. All (15/15) patient samples were confirmed positive by flow cytometry. No significant differences in expression levels were observed comparing CLL B-cells vs normal B-cells (n = 10). However, anti-NTB-A antibodies were capable of inducing CDC in white blood cells from CLL patients (n=5) but not in normal white blood cells (n=5), in addition to CDC activity against Raji cells. Preliminary data also suggests that the CDC effect is greater in purified CLL B-cells than purified normal B-cells. Conclusions: These results show that NTB-A is expressed in normal lymphocytes but not in other solid tissues or in CD34+ progenitor cells. B cell malignancies, including Non-Hodgkin lymphoma cells appear to express NTB-A. In particular CLL patient cells express NTB-A, and an anti-NTB-A mouse mAb is capable of inducing CDC, suggesting NTB-A may be a potential immunotherapeutic target. Further studies examining the expression patterns in hematologic malignancies are ongoing.

FISH Redoux — A Novel Way to Emulate CLL Leukemic Cells From Buffy Coat Samples

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3606-3606
Author(s):  
Stephanie A. Smoley ◽  
Patricia T. Greipp ◽  
Neil E. Kay ◽  
Tait D. Shanafelt ◽  
Jeanette E. Eckel-Passow ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
B Cell ◽  
Cell Population ◽  
Cell Sorting ◽  
Mayo Clinic ◽  
Buffy Coat ◽  
Fish Analysis ◽  
Cell Type ◽  
The Mean

Abstract Abstract 3606 Background: Cytogenetic abnormalities are important prognostic indicators in CLL. At Mayo Clinic, CLL FISH analyses are derived from buffy coat samples not purified for lymphocytes. Scoring is therefore performed on consecutive qualifying nuclei regardless of cell size, shape or morphology. This scoring may not reflect the percent of abnormal nuclei of the affected cell type, but rather the entire population of cells present in the sample. We sought to determine whether the percent abnormal nuclei in only the affected cell type (e.g. lymphocytes) of patients with CLL differed from that of the general cell population. Scoring only B-lymphocytes could increase the sensitivity of the test in patients with low B-cell counts, either early in their disease or after treatment. Cell sorting techniques could be used to reach this goal but can be expensive, labor intensive and add to completion time. We propose a “Poor Man's Cell Sorting” technique based on cell morphology when stained with 4',6-diamidino-2-phenylindole (DAPI). In CLL samples, both round and so called “lobed” cells are seen by DAPI staining but we hypothesize that the CLL B-cells typically present as perfectly round in shape (Fig. 1). Thus our hypothesis: if only the round cells are scored for a genetic defect, would this more accurately represent the malignant leukemic B-cell population and allow for enhanced disease status by FISH? Methods: After IRB approval, we identified 87 CLL patients (75% male; 25% female, mean age 62.4 y, range 43–89 y) in the Mayo Clinic CLL Database, who were seen at Mayo Clinic between March, 2002 - July, 2010. We selected patients known to have low level FISH abnormalities and who therefore should have a significant population of both lymphocytes and neutrophils. Selection criteria included <20×106 B-cells per microliter (by flow cytometry) of peripheral blood and ≤40% of interphase nuclei expressing a specific FISH abnormality. Although most of the 87 patients exhibited more than one FISH abnormality, we focused on only one FISH defect per patient for this study. The original specimen (slide or fixed cell pellet) was rescored for % abnormal nuclei among 100 consecutive round and 100 consecutive lobed (or multilobular) nuclei, using DAPI to identify nuclear architecture. These scores were compared to each other and to the original clinical FISH analysis (scored for 200 consecutive nuclei and not selected for nuclear morphology). Results: Among 87 cases, FISH signals were scored for 6q-(1), 11q-(9), +12(15), 13q-(58), 17p-(2) and 2 IGH rearrangements. In 86/87 cases, the abnormal lobed nuclei did not have FISH defects. One patient exhibited 35% +12 by clinical assay, 52% +12 in the round nuclei, and 11% by lobed nuclei. For all cases, the mean percentage of abnormal nuclei was greater in the round cells (46%) vs original scoring (23.6%). In 79/87 patients (91%), the % of abnormal nuclei was greater in the round cells vs original FISH (mean increase 24.3%; range 1.5–57%). One patient's score was the same in round cells vs original, and 7 patients exhibited fewer abnormal nuclei in the round cells vs original. For these 7 cases, the mean % abnormal nuclei was 5.6% for round nuclei vs 8.4% for original score (score differences ranged from 1 – 5.5%). Overall, by univariate regression analysis, round cells (p=0.0043) have a better correlation with % B-cells, ascertained by flow cytometry, than either the current clinical approach (p=0.0462) or the lobed-cell approach (p=0.4058). Discussion: In virtually all cases (99%), the abnormal FISH patterns were confined to the round nuclei, and the lobed nuclei were virtually always normal by FISH. For patients with <20×106 lymphocytes, selecting for round nuclei uniformly resulted in identification of a higher percentage of abnormal cells. Further studies, including comparison of our round nucleus approach to CLL FISH analysis to actual sorted B-lymphocyte cell selection and the association of this leukemic restricted estimation of abnormal FISH levels to clinical outcome are necessary. Given our findings, we believe that estimating FISH defects restricted to the leukemic B-cell population will become an important adjunct to cytogenetic analysis for patients with low lymphocyte counts, including those in clinical remission and those with minimal residual disease. Disclosures: No relevant conflicts of interest to declare.

TOSO-Deficient B Cells Show An Impaired NF-κB and Migration Signaling In Vivo

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1779-1779
Author(s):  
Alexandra Schulz ◽  
Christian P. Pallasch ◽  
Michael Hallek ◽  
Lukas P. Frenzel ◽  
Clemens Wendtner
Keyword(s):  
Gene Expression ◽  
Flow Cytometry ◽  
B Cells ◽  
Mouse Model ◽  
B Cell ◽  
Promoter Region ◽  
Targeted Mutagenesis ◽  
Luciferase Reporter ◽  
And Migration

Abstract Abstract 1779 Background: Our group firstly demonstrated that TOSO (FAIM3) is over-expressed in CLL compared to healthy B cell subsets as well as other B cell lymphomas. Furthermore, we detected a significant correlation of high TOSO expression to high lymphocyte count, unmutated IgVH status and Binet C, which are all markers for poor prognosis. TOSO has been described as pro-survival gene also in other settings. However, its mode of action is discussed controversially. Therefore, we aimed to elucidate the role of TOSO in B-cell specific gene expression by creating a knockdown mouse model. CD40 ligation and B cell receptor (BCR) activation influences TOSO expression and the fact that transcriptional regulation of TOSO is still unknown, we were eager to determine transcriptional factors that are directly responsible for the alterable TOSO levels. Methods: Faim3-floxed C57BL/6 FLP deleter mice were crossbred with CD19 specific Cre recombinase expressing mice. B-cells from the TOSOCD19−/− (KO) mice were isolated and gene expression was analyzed via mRNA based Illumina microchip array. Convincing results were verified by flow cytometry and blood count was carried out in addition. To determine the promoter region of TOSO, three overlapping DNA fragments (containing either NF-κB, Bcl-6 or both binding sites) upstream of the transcription start site of the first TOSO exon were cloned into a luciferase reporter vector lacking a promoter. Those constructs were transfected into HeLa cells. After 24 hours luciferase assays were performed. The involvement of NF-κB in the regulation of TOSO transcription was measured by TNFα stimulation of transfected cells prior to luminescence measurement. Targeted mutagenesis of the NF-κB binding site was performed to confirm the data. In addition, Bcl-6 expression vector was co-transfected for evaluation of repressing influence on TOSO expression. Results: In order to cover the functional part of TOSO, we generated a B-cell specific TOSOCD19−/− mouse model. Downstream effects of TOSO were validated via microarray-based gene expression analysis. Results displayed a clear clustering of deregulated genes compared to control mice. Nearly 400 genes showed expression alterations; genes involved in the NF-κB pathway and migration processes were downregulated in TOSOCD19−/−. These results were confirmed by flow cytometry analysis. The TOSO KO displayed also relevant effects on the hematopoietic system. Lymphocyte (p=0,0048), neutrophil (p=0,0007) and red blood cell counts (p=0,0051) were significantly decreased in the TOSOCD19−/− mice. Most important, the B-cell count was significantly reduced in TOSO-deficient settings (n=9; p=0,032). Since TOSO level seems to be so important for such fundamental pathways, investigation of gene expression regulation is mandatory. In situ analysis of the TOSO promoter region revealed NF-κB and Bcl-6 as promising results. Luciferase reporter assays including targeted mutagenesis confirmed the positive regulation of NF-κB and the repressing influence of Bcl-6 on TOSO expression significantly. Conclusions: We reveal for the first time a TOSO-dependent expression profile. We identified TOSO-dependent deregulated genes, which were involved in NF-κB signaling and migration, suggesting that TOSO represents an important factor in these pathways. Additionally, TOSO KO caused a decrease of peripheral B-cells in vivo. Furthermore, we identified NF-κB and Bcl-6 to regulate the TOSO expression in an opposite manner. Disclosures: No relevant conflicts of interest to declare.

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