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1.  Bcl-2 level as a biomarker for 13q14 deletion in CLL 
Deletion 13q14.3 is the most common cytogenetic abnormality in chronic lymphocytic leukemia (CLL). Previously it was reported that miR-15/16 is the target of 13q14 deletions and plays a tumor suppressor role by suppressing Bcl-2. Therefore, Bcl-2 expression was examined more closely to determine whether it would predict 13q14 deletion status.
A multi-color flow panel consisting of anti-Bcl-2/anti-lambda/anti-kappa/CD19/CD5/CD3/CD20 was performed. The ability of Bcl-2 to predict 13q14 deletion was tested using the conventional Bcl-2 index (c-index): mean fluorescence intensity (MFI) of CLL clone/MFI of residual T-cells. Fifty-four untreated CLL/MBL patients were studied. Bimodal Bcl-2 expression was evaluated to test the ability of Bcl-2 to detect intra-clonal heterogeneity. Other CLL prognostic markers including CD38, CD49d, CD26, and CD69 were evaluated. FISH was performed on selected sorted populations.
The Bcl-2 c-index strongly predicts del13q14 p<0.0001. A statistically significant association was observed between the percentage of cells carrying the deletion and the level of Bcl-2 expression p<0.05. Cells sorted based on Bcl-2 expression showed enrichment of both hemi-and homozygous del 13q14 cells. Also we observed that an alteration in Bcl-2 level over time predicts changes in 13q14 deletion status. And a statistically significant correlation between the bimodal pattern of CD69 expression and the presence of 13q14 deletion was found p<0.0001.
Bcl-2 expression using the c-index strongly predicts 13q14 deletion and can be used to distinguish homozygous, heterozygous, and diploid CLL clonal cells. Further systematic studies of this biomarker are needed for confirmation and expansion of these findings.
PMCID: PMC3963274  PMID: 23674504
chronic lymphocytic leukemia; Bcl-2; Flow cytometry; del 13q14; hemizygous/homozygous deletion
2.  Combined Normal Donor and CLL: Single tube ZAP-70 Analysis 
ZAP-70 has been identified as an independent prognostic marker in chronic lymphocytic leukemia (CLL). Based on our previous studies, we have developed a combined one-tube technology with multiple internal controls to optimize ZAP-70 assessment.
Forty-eight untreated CLL cases were examined for ZAP-70 expression using a modified 7-color one-tube assay. Normal donor (ND) whole blood is stained with CD3 APC-Cy7 and CD19 APC. In a second tube, patient whole blood is stained with CD5 PE-Cy7, CD19 PerCP-Cy5.5, and CD20 eFluor450. After surface staining and fixation, these two tubes are combined. After saponin permeabilization, the cells were stained with two anti-ZAP-70 clones (1E7.2/AF488 and SBZAP /PE). The results obtained from this modified tube were compared with those obtained concurrently using the non-mixed single sample tubes. Five different methods of ZAP-70 expression analysis were evaluated: percentage positive cells using ND T-cells as a reference; the internal patient T-cell/clone ratio; ND T-cell/clone ratio; clone/ ND B-cell ratio; and modified Z-index.
Overall, the combined patient and ND mix tube performed better than the non-mixed single sample tube. The strongest correlations between ZAP-70 expression and IGHV mutational status were seen with percentage positive ND T-cell, ND T-cell/clone ratio, clone/ND B-cell ratio for both 1E7.2 and SBZAP clone (p<0.0001).
The modified one tube method combining the ND and patient sample provides highly reliable results that correlate with the IGHV mutational status. This method should be considered as part of the next step in standardization of the ZAP-70 assay in CLL.
PMCID: PMC3407416  PMID: 22031337
Chronic Lymphocytic Leukemia; ZAP-70; Flow cytometry; One tube assay; IGHV; Cytogenetics
3.  Methodological Comparison of Two Anti-ZAP-70 Antibodies. 
ZAP-70 expression is a stage independent prognostic marker in CLL. However, inter-laboratory variation is large and there is neither a consensus nor regulatory approved methodology.
Two anti-ZAP70 clones (1E7.2 and SBZAP) were compared in 45 untreated CLL patients. Nine different methods for ZAP-70 expression analysis were evaluated: M1, isotype control to determine negative; M2, internal residual T-cell to determine positive; M3, normal donor (ND) T-cell to determine positive; M4, internal T-cell/clone ratio; M5, ND residual T-cell/clone ratio; M6, clone/normal remaining B-cell ratio; M7, clone/ND B- cell ratio; M8, CLL- Z score; M9, modified CLL-Z score. A scoring system was designed integrating both 1E7.2 and SBZAP clones to assign ZAP-70 expression.
The correlation coefficients for the four selected highest statistically significant methods were as follows (M1=0.71, M3=0.72, M7= 0.67, and M9=0.64). These four methods were used to generate a combined score. The two reagents showed agreement using the designed scoring system for 37/45 samples (82%) and 8/45 (18%) showed equivocal result with one of the two clones. Seven of the eight equivocal samples were resolved using the scoring system.
Four of the nine methods of analysis were compared for each reagent. The use of two independent ZAP-70 reagents increases analytical certitude and the scoring method aids in the resolution of equivocal results. The combined use of two reagents, four methods of analysis and a scoring method allowed for assignment of ZAP-70 expression in 44/45 samples (98%) tested and improved performance of this important prognostic assay.
PMCID: PMC3461319  PMID: 21472849
chronic lymphocytic leukemia; ZAP-70 score; Flow cytometry; 1E7.2/AF488; SBZAP/PE
4.  Improved ZAP-70 Assay Using Two Clones and Multiple Methods of Analysis 
In a companion methodological study, we compared two anti-ZAP-70 clones (1E7.2 AF 488 and SBZAP PE) and four selected methods of analysis. Clinical correlations are required for validation.
Multicolor flow-cytometric evaluation of ZAP-70, CD38, CD69, CD26, CD49d, and CD27 were tested in 45 untreated-CLL patients. Four methods of ZAP-70 expression analysis and a scoring system were designed. A correlation analysis between ZAP-70 score, IGHV mutational status, FISH, and these biomarkers was undertaken.
There is a strong correlation between ZAP-70 expression and IGHV mutational status. The scoring system for a single reagent (p= 0.0006 or 0.0002) favors the use of multiple methods of analysis. The combined score was substantially equivalent (p= 0.0003). There was also a correlation with del 13q14 (p=0.017) and trisomy12 (p=0.011). A correlation for CD38 and ZAP-70 score was seen using both 1E7.2 AF488 and SBZAP PE when ≥20% or ≥7% cutoff were used. A positive correlation was seen for CD49d expression using both reagents. CD26 showed a correlation with ZAP-70 expression but it was dependent upon the method of analysis. CD69 and CD27 showed no statistically significant correlation.
In our study population, ZAP-70 expression is the better predictor of the IGHV mutational status. The correlation analysis confirms that the use of four methods of analysis with a single reagent or both reagents is superior to the use of a single method of analysis. The routine use of CD38, CD49d, and CD26 will require standardization.
PMCID: PMC3407415  PMID: 21472850
chronic lymphocytic leukemia; ZAP-70; CLL Score System; flow cytometry; prognostic marker
5.  Quantitative detection of zeta-chain-associated protein 70 expression in chronic lymphocytic leukemia 
Leukemia & lymphoma  2012;54(3):10.3109/10428194.2012.715349.
Overexpression of zeta-chain-associated protein 70 (ZAP-70) was recently recognized as an independent prognostic marker for the aggressive form of chronic lymphocytic leukemia (CLL). The objective of this study was to demonstrate the feasibility and implementation of quantitative detection of ZAP-70 protein in B cells to clearly distinguish patients with CLL with the aggressive form of the disease. B cells were isolated from patient blood and lysed. Released ZAP-70 protein was detected using an immunomagnetic fluorescence assay. The assay protocol was developed using Jurkat cells and recombinant ZAP-70 (rZAP-70). The limit of detection was determined to be lower than 125 Jurkat cells and 39 pg of rZAP-70 protein. The signal response was linear over a wide dynamic range, from 125 to 40 000 Jurkat cells per test (R2 = 0.9987) and from 0 to 40 000 pg rZAP-70 protein per test (R2 = 0.9928). The results from 20 patients with CLL correlated strongly with flow cytometry analysis. Concordance between the two methods for positive and negative results was 100% (7/7) and 92% (12/13), respectively, while the overall concordance between the two methods was 95%. The assay reported here is a simple, reliable and reproducible method for quantitative detection of ZAP-70 in patient leukemic cells, without the need for cell fixation or permeabilization. The ZAP-70 signal was linear over a wide dynamic range, which we believe enables quantitative assessment of small changes in ZAP-70 expression over the course of the disease and in response to therapeutic intervention.
PMCID: PMC3862258  PMID: 22839722
Chronic lymphocytic leukemia (CLL); ZAP-70; flow cytometry; immunomagnetic fluorescence assay; Signalyte-II spectrofluorometer
6.  Immnuophenotypic and Gene Expression Analysis of Monoclonal B Cell Lymphocytosis Shows Biologic Characteristics Associated With Good Prognosis CLL 
Monoclonal B cell lymphocytosis (MBL) is a hematologic condition wherein small B cell clones can be detected in the blood of asymptomatic individuals. Most MBL have an immunophenotype similar to chronic lymphocytic leukemia (CLL), and “CLL-like” MBL is a precursor to CLL. We used flow cytometry to identify MBL from unaffected members of CLL kindreds. We identified 101 MBL cases from 622 study subjects; of these, 82 individuals with MBL were further characterized. Ninety-one unique MBL clones were detected: 73 CLL-like MBL (CD5+CD20dimsIgdim), 11 atypical MBL (CD5+CD20+sIg+), and 7 CD5neg MBL (CD5negCD20+sIgneg). Extended immunophenotypic characterization of these MBL subtypes was performed, and significant differences in cell surface expression of CD23, CD49d, CD79b, and FMC-7 were observed among the groups. Markers of risk in CLL such as CD38, ZAP70, and CD49d were infrequently expressed in CLL-like MBL, but were expressed in the majority of atypical MBL. Interphase cytogenetics was performed in 35 MBL cases, and del 13q14 was most common (22/30 CLL-like MBL cases). Gene expression analysis using oligonucleotide arrays was performed on 7 CLL-like MBL, and showed activation of B cell receptor associated pathways. Our findings underscore the diversity of MBL subtypes and further clarify the relationship between MBL and other lymphoproliferative disorders.
PMCID: PMC3164475  PMID: 21617698
7.  Variables in the Quantification of CD4 in Normals and Hairy Cell Leukemia Patients 
Quantitative flow cytometry (QFCM) is being applied in the clinical flow cytometry laboratory. Quantitative normal T-cell CD4 expression represents a biologic standard and quality control agent. However, low levels of CD4 expression were detected in normal T-cells in Hairy Cell Leukemia (HCL) samples.
The QuantiBrite System® was used to determine the level of CD4 expression (mean antibody bound per cell, ABC) in fresh and shipped HCL blood and fresh normal donor blood (NDB). The effects of shipping, lysing reagent, cell preparation method and antibody lot were evaluated.
Shipped HCL specimens (n = 69) had a significantly lower mean CD4 ABC of 38,788 (CV = 9.1%) compared to fresh specimens (n = 105) CD4 value of 40,330 (CV = 8.4%) (p < 0 .05). In NDB, significant differences were seen for fresh versus shipped specimens using the stain/lyse method but not for lyse/stain method. Consistent differences in CD4 ABC based upon antibody lot were observed in fresh HCL and NDB samples. Stain/lyse and lyse/stain methods using NH4Cl lyse were compared in NDB using identical samples and antibodies. The NDB CD4 ABC values obtained with the lyse (NH4Cl )/stain method (45,562, 3.7% CV) were lower than those obtained with the stain/lyse (NH4Cl) method (49,955, 3.3% CV) with p<0.001.
CD4 expression in HCL patient samples is not inherently different from that observed in NDB and therefore may serve as a biological control in clinical QFCM. Technical variables impact significantly on QFCM of CD4.
PMCID: PMC2976776  PMID: 20687201
8.  Common Occurrence of Monoclonal B-cell Lymphocytosis Among Members of High-Risk CLL Families 
British journal of haematology  2010;151(2):152-158.
Monoclonal B-cell lymphocytosis (MBL) is an asymptomatic haematological condition characterized by low absolute levels of B-cell clones with a surface immunophenotype similar to that of chronic lymphocytic leukaemia (CLL). In the general population, MBL increases with age with a prevalence of 5–9% in individuals over age 60 years. It has been reported to be higher among first-degree relatives from CLL families. We report results of multi-parameter flow cytometry among 505 first-degree relatives with no personal history of lymphoproliferative disease from 140 families having at least two cases of CLL. Seventeen percent of relatives had MBL. Age was the most important determinant where the probability for developing MBL by age 90 years was 61%. MBL clustered in certain families but clustering was independent of the number of known CLL cases in a family. As is the case with CLL, males had a significantly higher risk for MBL than did females (p=0.04). MBL patients had significantly higher mean absolute lymphocyte counts (2.4 × 109/l) and B-cell counts (0.53 × 109/l) than those with a normal B-cell immunophenotype. Our findings show that MBL occurs at a very high rate in high risk CLL families. Both the age and gender distribution of MBL are parallel to CLL, implying a shared inherited risk.
PMCID: PMC2966536  PMID: 20738309
chronic lymphocytic leukaemia; high risk families; monoclonal B-cell lymphocytosis; flow cytometry
9.  Genetic susceptibility variants for chronic lymphocytic leukemia 
There is strong and consistent evidence that a genetic component contributes to the etiology of chronic lymphocytic leukemia (CLL). A recent genome-wide association study (GWAS) of CLL identified 7 genetic variants that increased the risk of CLL within a European population.
We evaluated the association of these variants, or variants in linkage disequilibrium (LD) with these variants, with CLL risk in an independent sample of 438 CLL cases and 328 controls.
Of these 7 SNPs, 6 had p-trend < 0.05 and had estimated odds ratios (ORs) that were strikingly comparable to those of the previous study. Associations were seen for rs9378805 (OR = 1.47, 95% CI: 1.19, 1.80, p-trend = 0.0003) near IRF4 and rs735665 near GRAMD1B (OR= 1.47; 95% CI: 1.14, 1.89; p-trend = 0.003). However, no associations (P> 0.05) were found for rs11083846, nor were any found for any SNPs in LD with rs11083846.
Our results confirm the previous findings and further support the role of a genetic basis in the etiology of CLL; however, more research is needed to elucidate the causal SNP(s) and the potential manner in which these SNPs or linked SNPs function in CLL pathogenesis.
PMCID: PMC2852480  PMID: 20332261
IRF4; CLL; genetic association
10.  Genome-wide association study of follicular lymphoma identifies a risk locus at 6p21.32 
Nature genetics  2010;42(8):661-664.
To identify susceptibility loci for non-Hodgkin lymphoma (NHL) subtypes, we conducted a three-stage genome-wide association study. We identified two variants associated with follicular lymphoma (FL) in 1,465 FL cases/6,958 controls at 6p21.32 (rs10484561, rs7755224, r2=1.0; combined p-values=1.12×10-29, 2.00×10-19), providing further support that MHC genetic variation influences FL susceptibility. Confirmatory evidence of a previously reported association was also found between chronic lymphocytic leukemia/small lymphocytic lymphoma and rs735665 (combined p-value=4.24×10-9).
PMCID: PMC2913472  PMID: 20639881
11.  Familial Aspects of Chronic Lymphocytic Leukemia, Monoclonal B-Cell Lymphocytosis (MBL), and Related Lymphomas 
Families with multiple individuals affected with chronic lymphocytic leukemia (CLL) and other related B-cell tumors have been described in the literature. Familial CLL does not appear to differ from sporadic CLL in terms of prognostic markers and clinical outcome. While some environmental factors (such as farming related exposures and occupational chemicals) may increase risk of CLL, results of epidemiological studies have been generally inconsistent inconsistent and well-defined extrinsic risk factors are unknown. Large, population-based case-control and cohort studies have also shown significant familial aggregation of CLL and related conditions including non-Hodgkin lymphomas, especially other indolent lymphomas. The precursor condition, monoclonal B-cell lymphocytosis (MBL) also aggregates in CLL families. However because the baseline population risks for CLL and other indolent lymphomas are low, the absolute risk to a first-degree relative for developing CLL or a related disease is also low. Linkage studies have been conducted in high-risk CLL families to screen the whole genome for loci that contribute to susceptibility but no gene mutations have yet been identified by this method. Association studies of candidate genes have implicated several genes as being important in CLL but more studies are needed to verify these findings. Results from whole genome association are promising. The ability to conduct large scale genomic studies will play an important role in detecting susceptibility genes for CLL over the next few years and thereby help to delineate etiologic pathways.
PMCID: PMC3010372  PMID: 21191471
chronic lymphocytic leukemia; monoclonal b-cell lymphocytosis; familial risk; germ line susceptibility; environmental risk factors
12.  Prevalence of Monoclonal B-Cell Lymphocytosis: A Systematic Review 
Cytometry. Part B, Clinical cytometry  2010;78(Suppl 1):S10-S18.
Individuals with monoclonal B-cell lymphocytosis (MBL) have been identified in clinic outpatients, in unaffected relatives of patients with chronic lymphocytic leukemia (CLL), and in general populations. MBL and its relationship with CLL have been actively investigated over the last decade. This report systematically reviews the prevalence of MBL in the context of the populations studied and the evolution of laboratory methods used to define MBL.
To identify published studies that have assessed the prevalence of MBL, we systematically searched the MEDLINE® databases and consulted with members of the International MBL Study Group. We reviewed the 10 articles that were identified by this process. We abstracted information on study populations, laboratory tests, criteria for designating MBL, and the reported frequencies.
Three of the ten studies were published in 2009, three between 2007 and 2008, and four between 2002 and 2004. Reported prevalences varied widely, ranging from 0.12 to 18.2%. This variability was clearly associated with both the laboratory methods and the populations studied. MBL was more common among older individuals and kindred of persons with CLL. The most common MBL subtype was CLL-like MBL.
Large population-based studies of MBL that employ standardized laboratory methods with a consensus case definition are needed to assess prevalence and establish risk factors. These studies should include prospective follow-up of MBL cases to determine the relationship between MBL and CLL. Data from original studies should be reported in sufficient detail to allow future synthesis of information from multiple studies, such as meta-analysis.
PMCID: PMC2963430  PMID: 20839330
monoclonal B-cell lymphocytosis; MBL; chronic lymphocytic leukemia; CLL; prevalence; epidemiology
13.  Murine Models of CLL: Role of microRNA-16 in the NZB mouse model 
British journal of haematology  2007;139(5):645-657.
Mouse models are valuable tools in the study of human chronic lymphocytic leukemia (CLL). The New Zealand Black (NZB) strain is a naturally occurring model of late-onset CLL characterized by B cell hyperproliferation and autoimmunity early in life, followed by progression to CLL. Other genetically engineered models of CLL that have been developed include (NZB × NZW) F1 mice engineered to express IL5, mice expressing human TCL1A, and mice overexpressing both BCL2 and a tumour necrosis factor receptor associated factor. The applicability to human CLL varies with each model, suggesting that CLL is a multifactorial disease. Our work with the de novo NZB model has revealed many similarities to the human situation, particularly familial CLL. In NZB, the malignant clones express CD5, zap-70, and have chromosomal instability and germline Ig sequence. We also identified a point mutation in the 3’ flanking sequence of Mirn16-1, which resulted in decreased levels of the microRNA, miR-16 in lymphoid tissue. Exogenous restoration of miR-16 to an NZB malignant B-1 cell line resulted in cell cycle alterations, suggesting that the altered expression of Mirn15a/16-1 is an important molecular lesion in CLL. Future studies utilizing the NZB mouse could ascertain the role of environmental triggers, such as low dose radiation and organic chemicals in the augmentation of a pre-existing propensity to develop CLL.
PMCID: PMC2692662  PMID: 17941951
mouse models of CLL; NZB; microRNA

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