Expression patterns of CD200 and CD148 in leukemic B-cell chronic lymphoproliferative disorders and their potential value in differential diagnosis

Methodological and conceptual challenges to the flow cytometric classification of leukemic lymphoproliferative disorders

The diagnosis of leukemic B-cell lymphoproliferative disorders (B-LPDs) is made by integrating clinical, cytological, cytometric, cytogenetic, and molecular data. This leaves room for differences and inconsistencies between experts. In this study, we examine methodological and conceptual aspects of the flow cytometric classification of leukemic B-LPDs that could explain them. Among methodological aspects, we discuss (1) the different statistical tests used to select and evaluate markers, (2) how these markers are analyzed, (3) how scores are interpreted, (4) different degrees to which diagnostic information is used, and (5) and the impact of differences in study populations. Among conceptual aspects, we discuss (1) challenges to integrating different biological data points, (2) the under examination of the costs of misclassification (false positives and false negatives), and finally, (3) we delve into the impact of the lack of a true diagnostic gold standard and the indirect evidence suggesting poor reproducibility in the diagnosis of leukemic B-LPDs. We then outline current harmonization efforts and our personal approach. We conclude that numerous flow cytometry scores and diagnostic systems are now available; however, as long as the considerations discussed remain unaddressed, external reproducibility and interobserver agreement will not be achieved, and the field will not be able to move forward if a true gold standard is not found.

The potential differential diagnosis value and clinical significance of CD35 expression in B-chronic lymphoproliferative disorders

Background

Flow cytometry for immunophenotyping is the main method for diagnosing chronic lymphocytic leukemia (CLL). Differential diagnosis between CLL and other B-chronic lymphoproliferative disorders (B-CLPDs) is sometimes difficult. This study aimed to investigate whether cluster of differentiation 35 (CD35) could be a useful marker for the differential diagnosis of CLL and other B-CLPDs.

Methods

The CD35 expression on lymphoma cells from 516 B-CLPD patients (347 CLL, 169 other B-CLPDs) was investigated through flow cytometry analysis. Serum C3 and C4 levels in B-CLPD patients were also evaluated.

Results

The results showed that the expression percentage and mean fluorescence intensity of CD35 were reduced in CLL cases compared with other B-CLPD patients. Furthermore, CD35 <17% produced a sensitivity of 81.8% and a specificity of 88.4% for supporting the diagnosis of CLL. Additionally, the addition of CD35 to Matutes score improved the score's discriminative power. The sensitivity of the Matutes score was improved from 81.3% to 88.5%, and the accuracy was improved from 96.6% to 97.6%. Finally, 15.0% and 16.4% of CLL patients had defective serum C3 and C4 levels at diagnosis, respectively.

Conclusions

Evaluating CD35 expression could have potential differential diagnostic value in distinguishing CLL from other B-CLPDs, especially between CLL and mantle cell lymphoma (MCL).

Leukemic Variant of Mantle Cell Lymphoma: Clinical Presentation and Management

PURPOSE OF REVIEW

This review summarizes the unique presentation and management of the leukemic variant of mantle cell lymphoma (LV-MCL, also referred to as non-nodal MCL) and highlights the biologic and clinical differentiation from classical mantle cell lymphoma (cMCL) in biomarker expression, clinical features, prognosis, disease course, and treatment.

RECENT FINDINGS

Several studies have evaluated the gene expression profile of mantle cell lymphoma, differentiating LV-MCL from cMCL. The typical immunophenotypic profile is CD5-positive, SOX 11-negative, CD23-low, CD200-low, and cyclin D1 overexpressed. LV-MCL commonly has mutated immunoglobulin heavy chain variable region genes. Data on treatment of LV-MCL is limited to retrospective analyses; the ideal treatment for these patients is unknown although many have a clinically indolent, asymptomatic presentation and often may be observed for an extended period without active treatment. LV-MCL is a clinically and biologically distinct entity. Clinically, it must be distinguished from chronic lymphocytic leukemia and cMCL. Future prospective, randomized clinical trials are required to optimize management, define the initial treatment, and appropriately sequence treatment modalities.

The contribution of CD200 to the diagnostic accuracy of Matutes score in the diagnosis of chronic lymphocytic leukemia in limited resources laboratories

Flow cytometry immunophenotyping has an essential role in distinguishing chronic lymphocytic leukemia from other B-chronic lymphoproliferative disorders. Recently, CD200 is considered as a relatively consistent marker in chronic lymphocytic leukemia. We retrospectively assessed CD200 expression in 252 patients with B chronic lymphoproliferative disorders with four-color flow cytometry. CD200 expression estimation included the proportion of positive cells (≥30%) and the mean fluorescence intensity ratio. Additionally, we have incorporated CD200 into Matutes score, also replaced FMC7 and CD79b in an attempt to improve the score discriminative power. Of 252 patients enrolled, 199(79%) patients were classified as chronic lymphocytic leukemia and 53 (21%) as other B-chronic lymphoproliferative disorders. All chronic lymphocytic leukemia cases and 20 of 53 (37.7%) of other B-chronic lymphoproliferative disorders demonstrated high CD200 expression (≥30%). Further, CD200 (≥30%) revealed a higher accuracy in comparison to other markers in Matutes score (range: 51%–92.5%). Also, CD200 addition to the Matutes score has correctly recognized all 199 chronic lymphocytic leukemia cases including 10 atypical chronic lymphocytic leukemia cases. As for non-CLL cases, 20 of 53 attained a higher score, yet keeping the original diagnosis. Moreover, CD200 enhanced the diagnostic accuracy of Matutes score to 100%, and when included in a simplified 4-markers score, showed an accuracy of 99.8% compared to 99.4% of Matutes score. In conclusion, CD200 is an accurate diagnostic marker for chronic lymphocytic leukemia, and can refine the modified Matutes score accuracy when added with other markers.

The relative expression levels of CD148 and CD180 on clonal B cells and CD148/CD180 median fluorescence intensity ratios are useful in the characterization of mature B cell lymphoid neoplasms infiltrating blood and bone marrow - Results from a single centre pilot study

INTRODUCTION

The categorization of mature B cell neoplasms (MBN) infiltrating blood and bone marrow are met with difficulties. The inclusion of CD148 and CD180 in the routine flow cytometry/FCM panels has been suggested to refine the diagnosis. We studied the discriminatory ability of CD148 and CD180 median fluorescence intensity(MFI), CD148/CD180 ratio and their expression relative to T cells (CD148^ab/T , CD180^ab/T ), neutrophils (CD148^ab/gr , CD180^ab/gr ) and normal B cells (CD148^ab/n , CD180^ab/n ) in the differentiation of mature B cell neoplasms (MBN) especially non-chronic lymphocytic leukaemia (CLL).

METHODOLOGY

The flow cytometric (FCM) expression of CD148 and CD180 was studied prospectively in 102 patients (non-CLL; n = 72); diagnosed by a comprehensive panel of immunophenotypic and cytogenetic studies. The MFI and ratios were statistically compared across MBNs by Mann-Whitney U test. Cut-off values, sensitivity and specificity were calculated for significant parameters by receiver operator characteristic curve.

RESULTS

CD180MFI > 4.35 showed 100% sensitivity and 90.9% specificity for a diagnosis of marginal zone lymphoma (MZL) while, CD148/180 > 5.15 was 100% specific and 81.8% sensitive for lymphoplasmacytic lymphoma. CD148^ab/T (>4.3; 100% specificity, 83.4% sensitivity) and CD148^ab/gr (>1.1; 100% sensitivity, 90% sensitivity) were useful for differentiating blastoid-mantle cell lymphoma/MCL from diffuse large B cell lymphoma; while CD148MFI (≥20.25), CD148^ab/T (>3.35) and CD148^ab/gr (>0.95) showed >90% specificity and sensitivity for distinguishing MCL from CLL. Pairwise analysis also showed a good discriminant function of various parameters for distinguishing SMZL from other MBNs like FL, MCL as well as CLL.

CONCLUSIONS

The current study shows an excellent utility of CD148MFI, CD180MFI, their ratio and relative expression levels in the subcategorization of immunophenotypically related MBNs.

CD200 and Chronic Lymphocytic Leukemia: Biological and Clinical Relevance

CD200, a transmembrane type Ia glycoprotein belonging to the immunoglobulin protein superfamily, is broadly expressed on a wide variety of cell types, such as B lymphocytes, a subset of T lymphocytes, dendritic cells, endothelial and neuronal cells. It delivers immunosuppressive signals through its receptor CD200R, which is expressed on monocytes/myeloid cells and T lymphocytes. Moreover, interaction of CD200 with CD200R has also been reported to play a role in the regulation of tumor immunity. Overexpression of CD200 has been reported in chronic lymphocytic leukemia (CLL) and hairy cell leukemia but not in mantle cell lymphoma, thus helping to better discriminate between these different B cell malignancies with different prognosis. In this review, we focus on the role of CD200 expression in the differential diagnosis of mature B-cell neoplasms and on the prognostic significance of CD200 expression in CLL, where conflicting results have been published so far. Of interest, increasing evidences indicate that anti-CD200 treatment might be therapeutically beneficial for treating CD200-expressing malignancies, such as CLL.

Measurable residual disease in the treatment of chronic lymphocytic leukemia

Treatment outcomes of chronic lymphocytic leukemia (CLL) have improved since chemoimmunotherapy and novel drugs became available for CLL treatment; therefore, more sensitive methods to evaluate residual CLL cells in patients are required. Measurable residual disease (MRD) has been assessed in several clinical trials on CLL using flow cytometry, real-time quantitative PCR (RQ-PCR) with allele-specific oligonucleotide (ASO) primers, and high-throughput sequencing. MRD assessment is useful to predict the treatment outcomes in the context of chemotherapy and treatment with novel drugs such as venetoclax. In this review, we discuss major techniques for MRD assessment, data from relevant clinical trials, and the future of MRD assessment in CLL treatment.

Determination of CD43 and CD200 surface expression improves accuracy of B-cell lymphoma immunophenotyping

BACKGROUND

The Matutes score (MS) was proposed to differentiate chronic lymphocytic leukemia (CLL) from other B-cell non-Hodgkin lymphomas (B-NHLs). However, ambiguous immunophenotypes are common and remain a diagnostic challenge. Therefore, we evaluated the diagnostic benefit of measuring CD200 and CD43 expression together with the standard MS antigens.

METHODS

138 lymphoma patient samples and a validation cohort of 138 additive samples were classified according to the standard MS and further assigned with one or two additional points, for high CD200 and/or CD43 expression levels. The "classical" MS and the "Matutes score-extended" (MS-e) were categorized as high (4-5/6-7), intermediate (2-3/4-5), and low (0-1/0-3). Samples were reclassified into the MS-e with focus on ambiguous cases with an intermediate "classical" MS.

RESULTS

A total of 35 of 138 (25.4%) patient samples were assigned to the intermediate MS group and confirmed by histopathological reports as CLL (14/40.0%) and B-NHLs other than CLL (21/60%). MS-e analysis identified 13 of 14 (92.9%) of CLL cases (MS-e 4-5) and 18/21 (85.7%) non-CLL cases (MS-e ≤ 3) correctly. Overall, the sensitivity of the CLL diagnosis was significantly increased by application of MS-e compared to the "classical" MS (98.8% vs. 82.7%; p = 0.0009), while specificity of both methods was almost equal (94.7% vs. 98.3%; p = 0.4795). Of note, sole measurement of CD43 and CD200 on B-cells sufficiently differentiated CLL from non-CLL with a test accuracy superior to the "classical" MS (F1 score 96.2 vs. 93.6).

CONCLUSION

CD200 and CD43 have a high informative value in diagnostic immunophenotyping and facilitate the separation of CLL from other B-NHLs particularly in ambiguous cases.

Subtype Distribution, Clinical Features, and Survival in B-cell Chronic Lymphoproliferative Disorders in China: A Review of 1592 Cases

BACKGROUND

B-cell chronic lymphoproliferative disorders (B-CLPDs) are characterized by the sustained accumulation of monoclonal B cells. Limited studies have systematically described the clinical features and outcomes of the whole patient group, especially in Eastern populations.

PATIENTS AND METHODS

A total of 1592 patients with newly diagnosed B-CLPD were enrolled. Chronic lymphocytic leukemia (CLL) accounted for 39%, and Waldenström macroglobulinemia (WM), leukemic marginal zone lymphoma, follicular lymphoma (FL), and mantle cell lymphoma (MCL) constituted 13%, 13%, 9%, and 8% of cases, respectively.

RESULTS

The median age at diagnosis was 58 years, and the male/female ratio was 1.8:1. The 17p and 11q deletions were most common in MCL (36% and 17%, respectively), and 13q deletion and trisomy 12 were most frequent in CLL (35% and 21%, respectively). Patients with leukemic MCL had significantly worse survival than that of patients with other disease entities, with a 3-year overall survival (OS) of 58%, followed by 68.2% for WM/lymphoplasmacytic lymphoma. Those with CLL, leukemic marginal zone lymphoma, and FL had relatively favorable outcomes, with a 5-year OS > 80%. The survival of patients with B-CLPDs has improved over time with the emergence of novel drugs (3-year OS improvement from 82.1% to 92.2%). The improvement in survival mainly resulted from improvement among patients with MCL, WM/lymphoplasmacytic lymphoma, and FL. On multivariate analysis, only hemoglobin, lactate dehydrogenase, and 17p deletion were independently associated with survival (hazard ratio, 1.6, 2.0, and 3.1, respectively).

CONCLUSIONS

Comprehensive analysis of the clinical characteristics, immunophenotypic profiles, and cytogenetic features can be helpful in the differential diagnosis, especially for patients without a non-bone marrow biopsy specimen available. Universal prognostic factors could help with the early detection of high-risk patients and stratification for risk-adapted therapy.

Proteomics insights into the pathology and prognosis of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is an incurable malignant disease of B-lymphocytes characterized by drastically heterogeneous clinical courses. Proteomics is an advanced approach that allows a global profiling of protein expression, providing a valuable chance for the discovery of disease-related proteins. In the last 2 decades, several proteomics studies were conducted on CLL to identify aberrant protein expression underpinning the malignant transformation and progression of the disease. Overall, these studies provided insights into the pathology and prognosis of CLL and reveal protein candidates with the potential to serve as biomarkers and/or therapeutic targets of the tumor. The major findings reported in these studies are discussed here.

Consistency of the Moreau CLL score

BACKGROUND

The Moreau score is essential for the diagnosis of B-cell lymphoproliferative disorders (B-LPD).

METHODS

We assessed the consistency of the Moreau score in a series of 138 patients with at least two samples involved by a B-LPD (316 samples) other than germinal center-derived malignancies, hairy cell leukemia, and mantle cell lymphomas. Patients with evidence of two distinct B-LPDs were also excluded.

RESULTS

We found 53 inconsistencies in 44 of 138 (32%) patients. FMC7 was the most inconsistent (18 cases) and CD5 the least (5 cases). CD200 was inconsistent in 6 of 67 (9%) cases. The most important predictive factor for the finding of antigenic inconsistencies was sampling of a different anatomic site. Other factors, including number of samples, time between samples, or cytogenetic group, were not predictive. For the most part, these inconsistencies did not appear to be clinically relevant.

CONCLUSION

Inconsistencies in the Moreau score are common, supporting the importance of integrated laboratory diagnosis. However, the practical implications of these antigenic inconsistencies are probably limited.

Low expression of CD200 predicts shorter time-to-treatment in chronic lymphocytic leukemia

CD200, formerly known as OX-2, is a type I glycoprotein that is expressed on a variety of cell types. CD200 has been shown to be overexpressed in chronic lymphocytic leukemia (CLL). Although previous studies have confirmed the diagnostic value of CD200 in differentiating CLL from to other B-cell chronic lymphoproliferative disorders especially mantle cell lymphoma, whether CD200 has prognostic significance in CLL remains to be determined. We evaluated the mean fluorescence intensity (MFI) of CD200 in 307 consecutive, untreated patients with CLL in our center using flow cytometry. Using a CD200 MFI cutoff of 189.5, these cases could be divided into two groups. Patients with lower CD200 MFI (< 189.5) had a significantly shorter time-to-treatment (TTT) than those with higher CD200 MFI (≥ 189.5) (median TTT: 2 months vs 28 months, p = 0.0008). However, the effect of CD200 MFI on overall survival was not significant (CD200 MFI < 189.5: undefined vs CD200 MFI ≥ 189.5: undefined, P = 0.2379). In subgroup analysis, CD200 MFI retained its prognostic value in patients with favourable characteristics such as Binet stage A disease, mutated IGHV status, normal TP53 or negative CD38 expression. In conclusion, our study identified CD200 MFI as a potential prognostic factor in CLL.

Flow Cytometric Patterns of CD200 and CD1d Expression Distinguish CD10-Negative, CD5-Negative Mature B-Cell Lymphoproliferative Disorders

OBJECTIVES

The importance of distinguishing mature B-cell lymphoproliferative disorders (B-LPDs) is highlighted by the distinct treatments used for and varying prognoses seen in association with these different diseases. Immunophenotyping allows for accurate and efficient differentiation of many B-LPDs. Recently, we showed that CD200 is highly expressed in hairy cell leukemia (HCL) but not in marginal zone lymphoma (MZL), lymphoplasmacytic lymphoma (LPL), or hairy cell leukemia-variant (HCL-v). Here, we assessed the usefulness of a flow cytometric panel combining CD200 and CD1d with CD25, CD103, and CD11c to distinguish CD10-, CD5- B-LPDs.

METHODS

We analyzed the expression of CD200 and CD1d by flow cytometric analysis in 79 cases of CD10-, CD5- mature B-LPDs.

RESULTS

Distinct patterns of CD200 and CD1d expression were seen in the examined B-LPDs. HCL showed bright positivity for CD200 along with positive staining for CD1d, whereas HCL-v showed low levels of expression for both markers. LPL demonstrated positive staining for CD200 in combination with dim to negative staining for CD1d. In contrast, MZL was commonly positive for CD1d and negative for CD200.

CONCLUSIONS

Flow cytometric analysis of CD200 and CD1d, along with CD25, CD103, and CD11c, can aid in the diagnosis of CD10-, CD5- mature B-LPDs.

Hairy Cell Lymphoma: A Potentially Under-Recognized Entity

Hairy cell leukemia (HCL) is a low grade B-cell lymphoproliferative disorder that typically presents with splenomegaly, cytopenias, and diffuse bone marrow infiltration. There have been few cases in the literature of HCL presenting as lymphomas in extra-nodal locations, such as soft tissues and bones without circulating leukemic cells, splenomegaly, or iliac crest bone marrow involvement. We present an additional case presenting as a thoracic mass, and discuss potential diagnostic pitfalls and management of these rare cases.

Diagnosis of chronic lymphoproliferative disorders by flow cytometry using four-color combinations for immunophenotyping: A proposal of the brazilian group of flow cytometry (GBCFLUX)

BACKGROUND

Multiparametric flow cytometry (MFC) is a powerful tool for the diagnosis of hematological malignancies and has been useful for the classification of chronic lymphoproliferative disorders (CLPD) according to the WHO criteria. Following the purposes of the Brazilian Group of Flow Cytometry (GBCFLUX), the aim of this report was to standardize the minimum requirements to achieve an accurate diagnosis in CLPDs, considering the different economic possibilities of the laboratories in our country. Most laboratories in Brazil work with 4-fluorescence flow cytometers, which is why the GBCFLUX CLPD Committee has proposed 4-color monoclonal antibody (MoAb) panels.

METHODS/RESULTS

Panels for screening and diagnosis in B, T and NK lymphoproliferative disorders were developed based on the normal differentiation pathways of these cells and the most frequent phenotypic aberrations. Important markers for prognosis and for minimal residual disease (MRD) evaluation were also included. The MoAb panels presented here were designed based on the diagnostic expertise of the participating laboratories and an extensive literature review.

CONCLUSION

The 4-color panels presented to aid in the diagnosis of lymphoproliferative neoplasms by GBCFLUX aim to provide clinical laboratories with a systematic, step-wise, cost-effective, and reproducible approach to obtain an accurate immunophenotypic diagnosis of the most frequent of these disorders. © 2016 International Clinical Cytometry Society.