Study of gene expressions' correlation structures in subgroups of Chronic Lymphocytic Leukemia Patients

In chronic lymphocytic leukemia (CLL) the interaction of leukemic cells with the microenvironment ultimately affects patient outcome. CLL cases can be divided in two subgroups with different clinical course based on the mutational status of the immunoglobulin heavy variable (IGHV) genes: mutated CLL (M-CLL) and unmutated CLL (U-CLL). Since in CLL, the differentiated relation of genes between the two subgroups is of greater importance than the individual gene behavior, this paper investigates the differences between the groups' gene interactions, by comparing their correlation structures. Fisher's test and Zou's confidence intervals are employed to detect differences of correlation coefficients. Afterwards, networks created by the genes participating in most differences are estimated with the use of structural equation models (SEM). The analysis is enhanced with graph modeling in order to visualize the between group differences in the gene structures of the two subgroups. The applied methodology revealed stronger correlations between genes in U-CLL patients, a finding in line with related biomedical literature. Using SEM for multigroup analysis, different gene structures between the two groups of patients were confirmed. The study of correlation structures can facilitate the detection of differential gene expression profiles in CLL subgroups, with potential applications in other diseases. Comparison of correlations can be very useful in understanding the complex internal structural differences which signify the variations of a disease.

Encyclopedia of CLL Subsets - a Unique Bioinformatics Tool and Database for Analysis of Subsets of Stereotypical B-Cell Receptors in CLL

BACKGROUND

Chronic lymphocytic leukemia (CLL) is clinically and biologically highly variable disease which is closely related with multiple cellular and molecular markers, including sequence motifs of B-cell receptors. These motifs are highly similar (stereotyped) within one third of CLL patients and create homogeneous groups called stereotyped CLL subsets. The homogeneity is reflected also in clinical and biological characteristics of the disease. To facilitate access to the information about individual subsets, we have created a publicly available web-based tool Encyclopedia of CLL Subsets.

MATERIALS AND METHODS

The Encyclopedia of CLL subsets belongs to our bioinformatics platform Antigen Receptor Research Tool (ARResT) developed for analysis, clustering, and annotation of immunoglobulin sequences. To gather primary knowledge about the subsets, we have analyzed a dataset of 7,500 CLL patients published by Agathangelidis et al in 2012 [1]. We have created an overview of major stereotyped subsets and their characteristics. Additional clinical and cytogenomic information about individual subsets has been obtained by machine text processing of available literature from server PubMed and is regularly updated.

RESULTS

We have created a unique web-based application Encyclopedia of CLL Subsets available from http: //arrest.tools/subsets for an interactive access to the information about stereotyped CLL subsets. A user can obtain and compare basic information about the major subsets including their clinical and cytogenomic characteristics. These have been manually curated from machine processed results from PubMed database by experts in CLL research. Through the Encyclopedias user interface, user can also directly use our published tool ARResT/AssignSubsets to assign new immunoglobulin sequences to the major subsets.

CONCLUSION

The Encyclopedia of CLL Subsets is a publicly available online tool facilitating access to the most recent research knowledge about stereotyped CLL subsets and enabling analysis of own data and interpretation of the results. This gives the Encyclopedia a great potential for its use in clinical routine. This work was supported by Czech Ministry of Health grant No. 34272A. All rights reserved. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 1. 3. 2019 Accepted: 4. 3. 2019.

Subtype assignment of CLL based on B-cell subset associated gene signatures from normal bone marrow - A proof of concept study

Diagnostic and prognostic evaluation of chronic lymphocytic leukemia (CLL) involves blood cell counts, immunophenotyping, IgVH mutation status, and cytogenetic analyses. We generated B-cell associated gene-signatures (BAGS) based on six naturally occurring B-cell subsets within normal bone marrow. Our hypothesis is that by segregating CLL according to BAGS, we can identify subtypes with prognostic implications in support of pathogenetic value of BAGS. Microarray-based gene-expression samples from eight independent CLL cohorts (1,024 untreated patients) were BAGS-stratified into pre-BI, pre-BII, immature, naïve, memory, or plasma cell subtypes; the majority falling within the memory (24.5-45.8%) or naïve (14.5-32.3%) categories. For a subset of CLL patients (n = 296), time to treatment (TTT) was shorter amongst early differentiation subtypes (pre-BI/pre-BII/immature) compared to late subtypes (memory/plasma cell, HR: 0.53 [0.35-0.78]). Particularly, pre-BII subtype patients had the shortest TTT among all subtypes. Correlates derived for BAGS subtype and IgVH mutation (n = 405) revealed an elevated mutation frequency in late vs. early subtypes (71% vs. 45%, P < .001). Predictions for BAGS subtype resistance towards rituximab and cyclophosphamide varied for rituximab, whereas all subtypes were sensitive to cyclophosphamide. This study supports our hypothesis that BAGS-subtyping may be of tangible prognostic and pathogenetic value for CLL patients.

Drug-perturbation-based stratification of blood cancer

As new generations of targeted therapies emerge and tumor genome sequencing discovers increasingly comprehensive mutation repertoires, the functional relationships of mutations to tumor phenotypes remain largely unknown. Here, we measured ex vivo sensitivity of 246 blood cancers to 63 drugs alongside genome, transcriptome, and DNA methylome analysis to understand determinants of drug response. We assembled a primary blood cancer cell encyclopedia data set that revealed disease-specific sensitivities for each cancer. Within chronic lymphocytic leukemia (CLL), responses to 62% of drugs were associated with 2 or more mutations, and linked the B cell receptor (BCR) pathway to trisomy 12, an important driver of CLL. Based on drug responses, the disease could be organized into phenotypic subgroups characterized by exploitable dependencies on BCR, mTOR, or MEK signaling and associated with mutations, gene expression, and DNA methylation. Fourteen percent of CLLs were driven by mTOR signaling in a non-BCR-dependent manner. Multivariate modeling revealed immunoglobulin heavy chain variable gene (IGHV) mutation status and trisomy 12 as the most important modulators of response to kinase inhibitors in CLL. Ex vivo drug responses were associated with outcome. This study overcomes the perception that most mutations do not influence drug response of cancer, and points to an updated approach to understanding tumor biology, with implications for biomarker discovery and cancer care.

Differences between chronic lymphocytic leukaemia and small lymphocytic lymphoma cells by proteomic profiling and SNP microarray analysis

The majority of malignant cells in chronic lymphocytic leukaemia (CLL) circulate in the peripheral blood whereas small lymphocytic lymphoma (SLL) cells reside in tissues. The aim of this study was to detect differences in chemokine receptor expression, DNA single nucleotide polymorphism (SNP) microarray analysis and proteomic profiling to help elucidate why the cells remain in their respective environments. We identified by flow cytometric studies of chemokine receptors and DNA SNP microarray analysis significant differences between cells from CLL and SLL patients. Proteomic analysis revealed two potential markers (m/z 3091 and 8707) to distinguish the two disorders. There was a significantly greater expression of leucocyte trafficking receptor CXCR3 (CD183) and migration and homing receptor CXCR4 (CD184), and significantly lower expression of cell adhesion molecule integrin α₄ chain (CD49d), on CLL cells, compared with SLL cells. Conversely, SNP microarrays revealed greater numbers of copy-neutral loss of heterozygosity chromosomal aberrations, as well as gross chromosomal aberrations, in the SLL group, compared with the CLL group. These findings revealed that there was a significantly greater expression of trafficking, migration and homing receptors and significantly lower expression of adhesion molecules on CLL cells than on SLL cells, and that SLL may be a more progressive disease than CLL, with a more complex genotype.

Subtype distribution of lymphomas in South of Iran, analysis of 1085 cases based on World Health Organization classification

Lymphoma is one of the most common malignancies worldwide. Subtype distribution is different throughout the world. Some reports from the Middle East are in record. This article is trying to report the subtype distribution of lymphoma in Iran and compare it to that of Western, Far East Asian and Middle Eastern countries. A retrospective study was done on all lymphomas diagnosed in a large referral center in the South of Iran during a time period between 2009 and 2014. All diagnoses have been made according to 2008 WHO classification. A total number of 1085 cases with diagnoses of lymphoma retrieved. Twenty-nine cases (2.6 % of all) were precursor lymphoid neoplasm, 608 cases (56 % of all) were mature B cell neoplasm, 115 cases (10.5 % of all) were mature T and NK cell neoplasm, and 333 cases (30.6 % of all) were Hodgkin lymphoma. The six most frequent subtypes of mature B cell neoplasm were diffuse large B cell lymphoma, NOS (57 %), Burkitt lymphoma (7 %), small lymphocytic lymphoma (6.9 %), mantle cell lymphoma (5.7 %), extranodal marginal zone B cell lymphoma (5.2 %) and follicular lymphoma (3.6 %). Among mature T and NK cell neoplasm, mycosis fungoides was the most common type (43.4 %) followed by peripheral T cell lymphoma, NOS (20 %) and angioimmunoblastic T cell lymphoma (9.9 %). Of Hodgkin lymphoma cases, 90.6 % were classical type and 9.3 % were nodular lymphocyte predominant Hodgkin lymphoma. Extranodal involvement was seen in 42.2 % and GI tract was the most common site. Lymphoma frequencies were similar to that of Middle Eastern countries except for lower rate of follicular lymphoma and higher incidence of diffuse large B cell lymphoma, NOS and small lymphocytic lymphoma.

Clustering of Expression Data in Chronic Lymphocytic Leukemia Reveals New Molecular Subdivisions

Although the identification of inherent structure in chronic lymphocytic leukemia (CLL) gene expression data using class discovery approaches has not been extensively explored, the natural clustering of patient samples can reveal molecular subdivisions that have biological and clinical implications. To explore this, we preprocessed raw gene expression data from two published studies, combined the data to increase the statistical power, and performed unsupervised clustering analysis. The clustering analysis was replicated in 4 independent cohorts. To assess the biological significance of the resultant clusters, we evaluated their prognostic value and identified cluster-specific markers. The clustering analysis revealed two robust and stable subgroups of CLL patients in the pooled dataset. The subgroups were confirmed by different methodological approaches (non-negative matrix factorization NMF clustering and hierarchical clustering) and validated in different cohorts. The subdivisions were related with differential clinical outcomes and markers associated with the microenvironment and the MAPK and BCR signaling pathways. It was also found that the cluster markers were independent of the immunoglobulin heavy chain variable (IGVH) genes mutational status. These findings suggest that the microenvironment can influence the clinical behavior of CLL, contributing to prognostic differences. The workflow followed here provides a new perspective on differences in prognosis and highlights new markers that should be explored in this context.

ARResT/AssignSubsets: a novel application for robust subclassification of chronic lymphocytic leukemia based on B cell receptor IG stereotypy

MOTIVATION

An ever-increasing body of evidence supports the importance of B cell receptor immunoglobulin (BcR IG) sequence restriction, alias stereotypy, in chronic lymphocytic leukemia (CLL). This phenomenon accounts for ∼30% of studied cases, one in eight of which belong to major subsets, and extends beyond restricted sequence patterns to shared biologic and clinical characteristics and, generally, outcome. Thus, the robust assignment of new cases to major CLL subsets is a critical, and yet unmet, requirement.

RESULTS

We introduce a novel application, ARResT/AssignSubsets, which enables the robust assignment of BcR IG sequences from CLL patients to major stereotyped subsets. ARResT/AssignSubsets uniquely combines expert immunogenetic sequence annotation from IMGT/V-QUEST with curation to safeguard quality, statistical modeling of sequence features from more than 7500 CLL patients, and results from multiple perspectives to allow for both objective and subjective assessment. We validated our approach on the learning set, and evaluated its real-world applicability on a new representative dataset comprising 459 sequences from a single institution.

AVAILABILITY AND IMPLEMENTATION

ARResT/AssignSubsets is freely available on the web at http://bat.infspire.org/arrest/assignsubsets/

CONTACT

nikos.darzentas@gmail.com.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Chronic lymphocytic leukemia: a clinical review

IMPORTANCE

The most common leukemia is chronic lymphocytic leukemia (CLL). Every year, there are 15 000 new diagnoses and 5000 CLL deaths in the United States. Although therapeutic choices were once limited, treatment of this disease has vastly improved in the last decade.

OBJECTIVE

Evidence-based review of the diagnosis, staging, and treatment of CLL.

EVIDENCE REVIEW

PubMed, Cochrane Library, Scopus, and Google Scholar databases were searched through August 28, 2014. English-language peer-reviewed articles published between 2000-2014 were found using the keywords chronic lymphocytic leukemia, upfront therapy, upfront therapies, upfront therapeutic, upfront therapeutics, upfront treatment, front-line treatment, first-line treatment, front-line treatments, first-line treatments, front-line therapy, front-line therapies, randomized, randomized studies, randomized study, clinical trial, clinical trials, phase 3, and phase 3 clinical trial. Abstracts and presentations at scientific meetings were excluded. A total of 277 articles were retrieved, of which 24 met our predefined selection criteria; treatment recommendations were based on subsequent analysis of these 24 articles.

FINDINGS

The Rai and Binet systems for staging CLL were established in 1975 and 1977, respectively. However, they do not account for new disease categories such as monoclonal B-cell lymphocytosis (peripheral blood clonal lymphocytosis that does not meet other criteria for CLL). Two subsets of CLL are now recognized based on risk stratification involving molecular and cytogenetic analyses. Outcomes are improved by the addition of immunotherapy to combination chemotherapy for initial treatment in all subsets of treated patients. Overall response rates between 75% and 90% and complete responses between 22% and 45% are expected in the current era, with more than 80% of treated patients alive at 3 years. Overall, 5-year survival has increased to 66% from 60% (P < .001) in the past 10 years.

CONCLUSIONS AND RELEVANCE

Chemoimmunotherapy is the standard first-line option approach for CLL, the most common leukemia observed in adults. Treatment is initiated when the disease becomes symptomatic, and survival is high following treatment.

Development of a comprehensive prognostic index for patients with chronic lymphocytic leukemia

In addition to clinical staging, a number of biomarkers predicting overall survival (OS) have been identified in chronic lymphocytic leukemia (CLL). The multiplicity of markers, limited information on their independent prognostic value, and a lack of understanding of how to interpret discordant markers are major barriers to use in routine clinical practice. We therefore performed an analysis of 23 prognostic markers based on prospectively collected data from 1948 CLL patients participating in phase 3 trials of the German CLL Study Group to develop a comprehensive prognostic index. A multivariable Cox regression model identified 8 independent predictors of OS: sex, age, ECOG status, del(17p), del(11q), IGHV mutation status, serum β2-microglobulin, and serum thymidine kinase. Using a weighted grading system, a prognostic index was derived that separated 4 risk categories with 5-year OS ranging from 18.7% to 95.2% and having a C-statistic of 0.75. The index stratified OS within all analyzed subgroups, including all Rai/Binet stages. The validity of the index was externally confirmed in a series of 676 newly diagnosed CLL patients from Mayo Clinic. Using this multistep process including external validation, we developed a comprehensive prognostic index with high discriminatory power and prognostic significance on the individual patient level. The studies were registered as follows: CLL1 trial (NCT00262782, http://clinicaltrials.gov), CLL4 trial (ISRCTN 75653261, http://www.controlled-trials.com), and CLL8 trial (NCT00281918, http://clinicaltrials.gov).

Difficulty in classifying a B cell chronic lymphoproliferative disorder CD5+

We present the case of a 53 years old woman diagnosed with splenic marginal zone lymphomas with plasmacytic differentiation (after a lymph node biopsy), who, complained of mild asthenia, weight loss (about 10 kg in 9 months), spatial disorientation during the last period. The clinical examination revealed slight pallor, normal cardiovascular and respiratory examination; painful cervical, about 5cm in diameter and also non-painful inguinal lymphadenopathies, increased consistency, freely movable, about 2 cm in diameter. The patient presented enlarged liver (lower limit at 3 cm below the ribs) and spleen (inferior pole at the ombilicus). The laboratory tests showed leucocytosis with lymphocytosis-a clonal population of lymphocytes- CD19+, CD20low+, CD22+, CD5low+, CD24+, CD200low+, CD79B+, CD43-, FMC7+/-, CD10+/-, CD34-, BCL2+, TdT-, CD34-, CD10-, CD3-. We suggested the diagnosis of mantle cell lymphoma, blastoid variant and performed a bone marrow biopsy . The bone marrow biopsy excluded the diagnosis of mantel cell lymphoma, based on the absence of cycline D1. The histopathological appearance and the immunohistochemical tests (CD20+, CD79a+, CD5low+, TdT-, CD34-cycline D1-) suggested a blastoid variant of small lymphocytic lymphoma.

Risk categories and refractory CLL in the era of chemoimmunotherapy

Standardized criteria for diagnosis and response evaluation in chronic lymphocytic leukemia (CLL) are essential to achieve comparability of results and improvement of clinical care. With the increasing range of therapeutic options, the treatment context is important when defining refractory CLL. Refractory CLL has been defined as no response or response lasting ≤ 6 months from last therapy. This subgroup has a very poor outcome, and many trials use this group as an entry point for early drug development. With the intensification of first-line regimens, the proportion of patients with refractory CLL using these criteria decreases. This has immediate consequences for recruitment of patients into trials as well as salvage strategies. Conversely, patients who are not refractory according to the traditional definition but who have suboptimal or short response to intense therapy also have a very poor outcome. In this Perspective, we discuss recent results that may lead to a reassessment of risk categories in CLL focusing on fit patients who are eligible for all treatment options. We cover aspects of the history and biologic basis for refractory CLL and will focus on how emerging data on treatment failure from large trials using chemoimmunotherapy may help to define risk groups in CLL.

Immunophenotypic patterns of childhood acute leukemias in Indonesia

BACKGROUND

Immunophenotyping, as suggested by WHO, may improve diagnosis of childhood leukemia since it offers a better classification of the hematopoietic lineage of malignant cells as compared to morphology. Therefore, we aimed to determine the proportion of the immunophenotypic subtypes of acute leukemia in Indonesian children.

METHODS

Samples were obtained from patients (0-14 years of age) in 4 hospitals in Indonesia. We analyzed 541 suspected leukemia samples presented over a 4-year period (March 2006 - July 2010) by flow cytometry. Immunophenotyping allowed classification into acute myeloid leukemia (AML) and ALL (B-lineage and T-lineage ALL).

RESULTS

Of 541 samples, 136 were tested using a single color method and 405 with a three-color method. Concordance with morphology was very good (?=0.82) using the three-color method with a panel of 15 monoclonal antibodies (n=387). A relatively high percentage of acute leukemia was classified as AML (23%). Of the ALL samples 83% were B-lineage ALL and 17% T- lineage ALL. Nine out of 239 morphological ALL were labeled AML, and 12/79 morphological AML were in fact ALL.

CONCLUSION

Immunophenotyping in a multi-center study proved feasible and appears particularly important for prognostic assessment of childhood leukemia in low income countries such as Indonesia.

Expression of mutated IGHV3-23 genes in chronic lymphocytic leukemia identifies a disease subset with peculiar clinical and biological features

PURPOSE

B-cell chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease whose outcome can be foreseen by investigating the mutational status of immunoglobulin heavy chain variable (IGHV) genes. Moreover, a different prognosis was reported for CLL expressing specific IGHV genes in the context or not of stereotyped B-cell receptors. Here we investigated novel associations between usage of specific IGHV genes and clinical features in CLL.

EXPERIMENTAL DESIGN

Among 1,426 CLL-specific IG-rearrangements, stereotyped B-cell receptor clusters never utilized the IGHV3-23 gene. Given this notion, this study was aimed at characterizing the IGHV3-23 gene in CLL, and identifying the properties of IGHV3-23-expressing CLL.

RESULTS

IGHV3-23 was the second most frequently used (134 of 1,426) and usually mutated (M; 109 of 134) IGHV gene in our CLL series. In the vast majority of M IGHV3-23 sequences, the configuration of the 13 amino acids involved in superantigen recognition was consistent with superantigen binding. Clinically, M IGHV3-23 CLL had shorter time-to-treatment than other M non-IGHV3-23 CLL, and multivariate analyses selected IGHV3-23 gene usage, Rai staging, and chromosomal abnormalities as independent prognosticators for M CLL. Compared with M non-IGHV3-23 CLL, the gene expression profile of M IGHV3-23 CLL was deprived in genes, including the growth/tumor suppressor genes PDCD4, TIA1, and RASSF5, whose downregulation is under control of miR-15a and miR-16-1. Accordingly, relatively higher levels of miR-15a and miR-16-1 were found in M IGHV3-23 compared with M non-IGHV3-23 CLL.

CONCLUSIONS

Altogether, expression of the IGHV3-23 gene characterizes a CLL subset with distinct clinical and biological features.

Recurrent cytogenetic findings in subsets of patients with chronic lymphocytic leukemia expressing IgG-switched stereotyped immunoglobulins

We report a remarkable association of recurrent (stereotyped) cytogenetic aberrations with two subsets of chronic lymphocytic leukemia (CLL) cases expressing IgG-switched, stereotyped B-cell receptors (BCRs). Comparison with cases with heterogeneous BCRs showed that these recurrent cytogenetic aberrations were subset-biased. These findings further support a role for antigen in CLL development.

ZAP-70 protein expression and CD38 positivity in B-cell chronic lymphocytic leukemia

BACKGROUND

The clinical course, disease progression, and survival of B-cell chronic lymphocytic leukemia (B-CLL) have been correlated with immunoglobulin heavy-chain variable region mutation status. The biologic parameters 70-kDa zeta-associated protein (ZAP-70) and CD38 expression are easier and faster surrogate markers for mutational status.

OBJECTIVE

To assess retrospectively ZAP-70 expression in B-CLL cells using flow cytometry and examine its relationship with CD38 expression and the median time from diagnosis to initial therapy.

METHODS

Ninety-four unselected patients who had their follow-up in the outpatient clinic from 2004 to 2005 were reviewed for immunophenotyping ZAP-70 and CD38 expression. Direct immunolabeling with clone 2E3.2, isotype IgG2a, enabled easy quantification of ZAP-70 by flow cytometry in association with CD38 expression; in addition, the mean fluorescence intensity ratio (MFIR) of CD19+CD5+ B-CLL cells compared to an isotype control monoclonal antibody was determined.

RESULTS

ZAP-70 expression levels in B-CLL cells varied widely (0.3-99%). The median time to therapy was significantly shorter for the 54 patients with 20% or more ZAP-70+ cells (30 months) than for the 40 patients with less than 20% ZAP-70+ cells (median time to treatment not reached). The optimal MFIR for classifying patients as ZAP-70+ was 2. Thirty-two patients had a threshold of ZAP-70+CD38+ greater than 30%, with a median time from diagnosis to treatment of 19 months. Regardless of CD38 expression level, CD38 and ZAP-70 expressions were significantly associated. The median interval from diagnosis to initial therapy was 16.2 months for ZAP-70+CD38+ patients, 60 months for ZAP-70+CD38- or ZAP-70-CD38+ patients, and had not yet been reached for ZAP-70-CD38- patients.

CONCLUSION

The association of ZAP-70+CD19+CD5+ B-CLL cells and percentage of CD38+CD19+CD5+ B-CLL cells evaluated by flow cytometry provide reliable methods that could be introduced into a routine diagnostic B-CLL panel to predict outcome.

Flow cytometry for ZAP-70: New colors for chronic lymphocytic leukemia

ZAP-70 has become one of the most studied prognostic markers in Chronic Lymphocytic Leukemia (CLL). ZAP-70 is remarkable in many ways: ZAP-70 has been identified as the best discriminating gene between prognostically distinct CLL subtypes using large scale gene expression profiling; ZAP-70 has been shown to enhance signal transduction in CLL B-cells and therefore could contribute to disease progression; and ZAP-70 is one of the rare examples of an intracellular target considered for clinical flow cytometry. This issue attests to the enormous effort and the steady progress made in overcoming technical challenges of testing for ZAP-70 expression and sets the foundation for a successful translation of this important marker into clinical practice. Despite the best effort, one will likely have to accept that not all cases can be clearly assigned to one or the other group, given that ZAP-70 expression between CLL patients falls along a continuum from absent to high. Nevertheless, ZAP-70 expression could become a key parameter to guide patients towards risk adapted treatment strategies in prospective clinical trials.

Fine needle aspiration cytology and flow cytometry in the diagnosis and subclassification of non-Hodgkin's lymphoma based on the World Health Organization classification

OBJECTIVE

To determine the usefulness of fine needle aspiration cytology (FNAC) in combination with flow cytometry on the new World Health Organization (WHO) classification of malignant lymphoma.

STUDY DESIGN

Smears and flow cytometry reports of patients who underwent both methods at the same time were independently examined. Both methods were classified according to the new WHO classification of malignant lymphoma.

RESULTS

A group of 131 smears were examined. In 89 cases exact diagnosis was made by cytomorphology. Twenty-five cases were not classified exactly or were classified incorrectly, resulting in a sensitivity of 96.4% and a specificity of 85%. With flow cytometry, only 30 of 131 patients could be classified exactly, resulting in a sensitivity of 27% and specificity of 100%, respectively. The combination of methods showed a sensitivity of 85% and specificity of 100%.

CONCLUSION

The combination of FNAC and flow cytometry obtained by FNAC can distinguish between benign and malignant lymphoid infiltrates and support a diagnosis of lymphoma.

Reversible anergy of sIgM-mediated signaling in the two subsets of CLL defined by VH-gene mutational status

The 2 subsets of chronic lymphocytic leukemia (CLL), of worse or better prognosis, likely derive from pre-GC unmutated B cells, or post-GC mutated B cells, respectively. Different clinical behavior could relate to the ability of tumor cells to respond to surface (sIg)–mediated signals. Unmutated cases (U-CLL) have an increased ability to phosphorylate p72Syk in response to sIgM ligation compared to mutated cases (M-CLL). We now confirm and further investigate this differential signaling in a large cohort by [Ca2+]i mobilization. Cases responding to sIgM ligation express higher levels of CD38, ZAP-70, and sIgM. However, CD38 does not influence signaling in vitro or associate with response in bimodal CD38-expressing cases. Similarly, ZAP-70 expression is not required for response in either U-CLL or M-CLL. Strikingly, partially or completely anergized sIgM responses from each subset can recover both sIgM expression and signal capacity spontaneously in vitro or following capping/endocytosis. This provides direct evidence for engagement of putative antigen in vivo. Signaling via sIgD differs markedly being almost universally positive in both U-CLL and M-CLL, with no association with CD38 or ZAP-70 expression. Downstream signaling pathways, therefore, appear intact in CLL, locating anergy to sIgM, mainly in M-CLL. Integration of differential isotype-specific effects mediated by (auto)antigen may determine tumor behavior.