The bone marrow plasma cell labeling index by flow cytometry

[Expression of CD45 in newly diagnosed multiple myeloma and the relationship with prognosis]

目的

观察CD45在初诊多发性骨髓瘤（MM）患者中的表达，探讨其与MM疗效和预后的关系。

方法

回顾性分析2010年1月至2017年1月河南省人民医院收治的130例初诊MM患者骨髓异常浆细胞中CD45的表达情况，对CD45⁺与CD45⁻患者的疗效和预后进行比较。

结果

①130例初诊MM患者中CD45⁺组33例（25.38%），CD45⁻组97例（74.62%）。②CD45⁺组和CD45⁻组的客观缓解率（ORR）分别为33.33%和64.95%，差异有统计学意义（P=0.002）；以硼替佐米为基础方案治疗的患者，CD45⁺组和CD45⁻组的ORR分别为35.71%和66.25%，差异有统计学意义（P=0.005）。③130例MM患者的中位无进展生存（PFS）时间为33.3（95%CI 6.0~69.0）个月，中位总生存（OS）时间为36.3（95%CI 6.0~78.0）个月，CD45⁺组与CD45⁻组的中位PFS时间分别为29.8（95%CI 10.0~59.0）个月和34.5（95%CI 6.0~69.0）个月，差异有统计学意义（χ²=14.59，P<0.001），中位OS时间分别为32.5（95%CI 10.0~68.0）个月和37.6（95%CI 6.0~78.0）个月，差异有统计学意义（χ²=11.42，P=0.001）；接受硼替佐米的患者中，CD45⁺组与CD45⁻组的中位PFS分别为30.3（95%CI 10.0~59.0）个月和36.3（95%CI 6.0~69.0）个月，差异有统计学意义（χ²=14.75，P=0.001）。中位OS时间分别为34.0（95%CI 10.0~68.0）个月和39.5（95%CI 6.0~78.0）个月，差异有统计学意义（χ²=10.62，P=0.001）。④Cox风险回归模型分析显示血肌酐≥176.8 µmol/L[HR=2.723（95%CI 1.744~6.723），P=0.001]、CD45阳性[HR=1.330（95%CI 1.067~1.804），P=0.008]，LDH ≥ 220 IU/L[HR=1.308（95%CI 1.160~2.417），P=0.015]是独立于其他临床指标的预后危险因素。

结论

CD45阳性是MM患者的预后不良因素。硼替佐米不能改善CD45⁺MM患者的不良预后。

The prognostic significance of CD45 expression by clonal bone marrow plasma cells in patients with newly diagnosed multiple myeloma

Evaluation of clonal plasma cells (PCs) in the bone marrow (BM) of multiple myeloma (MM) patients reveals two distinct clonal PC populations based on the presence or absence of CD45 expression. We explored the prognostic significance of CD45 expression by clonal PCs in the BM of MM patients in the era of novel agent therapy. All 156 MM patients seen at the Mayo Clinic, Rochester from 2009 to 2011 who had their BM evaluated by multiparametric flow cytometry were included. Patients whose BM had ≥20% of the clonal PCs expressing CD45 were classified as CD45 positive (+) and the rest as CD45 negative (-). Of these patients, the median overall survival (OS) for patients in the CD45 (+) group (n=43, 28%) was 38 months versus not reached for the CD45 (-) group (n=113, 72%) (P=0.009). In a multivariable analysis, CD45 (+) status was an independent predictor of inferior OS among newly diagnosed patients with MM. CD45 expression may be a surrogate for a more aggressive phenotype of MM and warrants further investigation.

Role of flow cytometry of peripheral blood and bone marrow aspirates in early myeloma

Flow cytometric immunophenotyping (FCM) of multiple myeloma (MM) is commonly accepted in academic centers as providing clinically significant information and is becoming increasingly utilized in the private setting. FCM has established clinical relevance in the following: (1) differential diagnosis of MM from other plasma cell dyscrasias; (2) differentiating MM from lymphoplasmacytic lymphoma (LPL) and other non-Hodgkin lymphomas; (3) diagnosis of unusual cases of myeloma (eg, to confirm the diagnosis of rare cases of IgM MM); (4) determining the risk of progression of monoclonal gammopathy of uncertain significance (MGUS) and smoldering MM; (5) prognostication in MM; and (6) minimal residual disease detection (MRD) post therapy. FCM may have an emerging role in the enumeration of abnormal plasma cells in diagnosis of MM, but further studies are needed. We review the clinical value of FCM in evaluation of peripheral blood and bone marrow in early myeloma.

Immunophenotyping in multiple myeloma and related plasma cell disorders

Plasma cell disorders form a spectrum ranging from the asymptomatic presence of small monoclonal populations of plasma cells to conditions like plasma cell leukemia and multiple myeloma, in which the bone marrow can be replaced by the accumulation of neoplastic plasma cells. Immunophenotyping has become an invaluable tool in the management of hematological malignancies and is increasingly finding a role in the diagnosis and monitoring of plasma cell disorders. Multiparameter flow cytometry has evolved considerably during the past decade with an increasing ability to screen large numbers of events and to detect multiple antigens at the same time. This, along with a better understanding of the phenotypic heterogeneity of the clonal plasma cells in different disorders, has made immunophenotyping an indispensible tool in the diagnosis, prognostic classification and management of plasma cell disorders. This book chapter addresses the approaches taken to evaluate monoclonal plasma cell disorders, and the different markers and techniques that are important for the study of these diseases.

TG101209, a novel JAK2 inhibitor, has significant in vitro activity in multiple myeloma and displays preferential cytotoxicity for CD45+ myeloma cells

Interaction of myeloma cells with the bone marrow microenvironment is mediated in large part through different cytokines, especially VEGF and IL6. These cytokines, especially IL6, leads to upregulation of the JAK/STAT pathway in myeloma cell, contributing to increased proliferation, decreased apoptosis, and acquired drug resistance. Here, we examined the preclinical activity of a novel JAK2 inhibitor TG101209. TG101209 induced dose- and time-dependent cytotoxicity in a variety of multiple myeloma (MM) cell lines. The induction of cytotoxicity was associated with inhibition of cell cycle progression and induction of apoptosis in myeloma cell lines and patient-derived plasma cells. Evaluation of U266 cell lines and patient cells, which have a mix of CD45 positive and negative cells, demonstrated more profound cytotoxicity and antiproliferative activity of the drug on the CD45+ population relative to the CD45- cells. Exploring the mechanism of action of TG101209 indicated downregulation of pJak2, pStat3, and Bcl-xl levels with upregulation of pErk and pAkt levels indicating cross talk between signaling pathways. TG101209, when used in combination with the PI3K inhibitor LY294002, demonstrated synergistic cytotoxicity against myeloma cells. Our results provide the rationale for clinical evaluation of TG101209 alone or in combination with PI3K/Akt inhibitors in MM.

2006 Bethesda International Consensus recommendations on the flow cytometric immunophenotypic analysis of hematolymphoid neoplasia: medical indications

The clinical indications for diagnostic flow cytometry studies are an evolving consensus, as the knowledge of antigenic definition of hematolymphoid malignancies and the prognostic significance of antigen expression evolves. Additionally the standard of care is not routinely communicated to practicing clinicians and diagnostic services, especially as may relate to new technologies. Accordingly there is often uncertainty on the part of clinicians, payers of medical services, diagnostic physicians and scientists as to the appropriate use of diagnostic flow cytometry. In an attempt to communicate contemporary diagnostic utility of immunophenotypic flow cytometry in the diagnosis and follow-up of patients with hematolymphoid malignancies, the Clinical Cytometry Society organized a two day meeting of international experts in this area to reach a consensus as to this diagnostic tool. This report summarizes the appropriate use of diagnostic flow cytometry as determined by unanimous approval of these experienced practitioners.

Flow cytometric immunophenotyping for hematologic neoplasms

Flow cytometric immunophenotyping remains an indispensable tool for the diagnosis, classification, staging, and monitoring of hematologic neoplasms. The last 10 years have seen advances in flow cytometry instrumentation and availability of an expanded range of antibodies and fluorochromes that have improved our ability to identify different normal cell populations and recognize phenotypic aberrancies, even when present in a small proportion of the cells analyzed. Phenotypically abnormal populations have been documented in many hematologic neoplasms, including lymphoma, chronic lymphoid leukemias, plasma cell neoplasms, acute leukemia, paroxysmal nocturnal hemoglobinuria, mast cell disease, myelodysplastic syndromes, and myeloproliferative disorders. The past decade has also seen refinement of the criteria used to identify distinct disease entities with widespread adoption of the 2001 World Health Organization (WHO) classification. This classification endorses a multiparametric approach to diagnosis and outlines the morphologic, immunophenotypic, and genotypic features characteristic of each disease entity. When should flow cytometric immunophenotyping be applied? The recent Bethesda International Consensus Conference on flow cytometric immunophenotypic analysis of hematolymphoid neoplasms made recommendations on the medical indications for flow cytometric testing. This review discusses how flow cytometric testing is currently applied in these clinical situations and how the information obtained can be used to direct other testing.

CD45 expression by bone marrow plasma cells in multiple myeloma: clinical and biological correlations

Multiple myeloma (MM) is characterized by accumulation of clonal plasma cells (PCs). CD45, a key regulator of antigen-mediated signaling and activation in lymphocytes, is present in early stages of PCs development. We studied CD45 expression on MM PCs by flow cytometry, correlating it to important biological disease characteristics. Additionally, we examined the expression of various adhesion molecules on PCs. A total of 75 patients with untreated MM (29), relapsed MM (17), smoldering MM (12), and monoclonal gammopathy of undetermined significance (MGUS) (17) were studied. The proportion of PCs expressing CD45 was higher among those with early disease (MGUS or smoldering MM) compared to those with advanced disease (new or relapsed MM) (43 vs 22%; P=0.005). Among those with advanced disease, patients with bone lesions had a lower percentage of CD45-positive (CD45+) PCs; 14 vs 34% (P=0.02). Patients with high-grade angiogenesis had a lower percentage of CD45+ PCs; 13 vs 31% (P=0.03). The median overall survival for the CD45+ group (>20% PCs positive) was 39 vs 18 months for the CD45-negative (CD45-) group (P=0.07). The expression of CD138, CD56 and CD54 were higher among the CD45- PCs. This study demonstrates important biological correlates of CD45 expression on myeloma cells.

Phenotypic characterization of the human myeloma cell growth fraction

In this study we quantified the proliferation rate of normal and malignant plasma cells (PCs) by ex vivo incorporation of 5-bromo-2'-deoxyuridine (BrdU; labeling index, LI) using flow cytometry. We show that all bone marrow PCs, either normal or malignant, include a subset of proliferating PCs present within the CD45(bright) fraction. Indeed, medullary normal and malignant PCs were always heterogeneous for CD45 expression, and proliferation was always restricted primarily to the CD45(bright) compartment. Moreover, an inverse correlation was found between LI or CD45 and B-cell lymphoma 2 (Bcl-2) in both malignant and normal PCs, the most proliferating CD45(bright) PCs have the lowest Bcl-2 expression. We investigated expression of molecules of interest in multiple myeloma (MM)-that is, CD138, CD19, CD20, CD27, CD28, CD56, and CD11a-to further characterize the CD45(bright) fraction. Among all of these molecules, only CD11a was exclusively expressed by CD45(bright) proliferating myeloma cells. In conclusion, proliferating myeloma cells are characterized by the specific CD45(bright) CD11a(pos) Bcl-2(low) phenotype.

Persistence of recipient plasma cells and anti-donor isohaemagglutinins in patients with delayed donor erythropoiesis after major ABO incompatible non-myeloablative haematopoietic cell transplantation

Delayed donor erythropoiesis and pure red-cell aplasia (PRCA) complicate major-ABO mismatched non-myeloablative allogeneic stem-cell transplantation. To characterize these events, we analysed red-cell serology and chimaerism in lymphohaematopoietic lineages, including plasma cells and B cells, in 12 consecutive major-ABO incompatible transplants following cyclophosphamide/fludarabine-based conditioning. Donor erythropoiesis was delayed to more than 100 days in nine (75%) patients including six (50%) who developed PRCA. During PRCA, all patients had persistent anti-donor isohaemagglutinins and recipient plasma cells (5-42%), while myeloid and T cells were completely donor in origin. In contrast, B-cell chimaerism was frequently full-donor when significant anti-donor isohaemagglutinins persisted. Four patients with early mixed haematopoietic chimaerism and the prolonged presence of anti-donor isohaemagglutinins and recipient plasma cells developed delayed-onset (>100 days post-transplant) red cell transfusion dependence and PRCA after myeloid chimaerism converted from mixed to full donor. These findings confirm that donor-erythropoiesis is impacted by temporal disparities in donor immune-mediated eradication of recipient lymphohaematopoietic cells during major-ABO incompatibility and suggest that plasma cells are relatively resistant to graft-versus-host haematopoietic effects.

Flow cytometry in lymphoma diagnosis and prognosis: useful?

Flow cytometry has become an important tool in the diagnosis of mature lymphoid neoplasms and the determination of prognosis in selected cases. The advantages of flow cytometry are based largely on its ability to analyse, rapidly and simultaneously, multiple cell properties in a quantitative manner. Flow cytometric immunophenotyping is useful in diagnosing lymphoma under the WHO classification system, where lymphoid neoplasms are separated into distinct clinical entities based upon morphology, immunophenotype, genetic abnormalities and clinical features. Flow cytometry can quantify the expression of proteins associated with a good or poor prognosis, detect multidrug resistance, and measure cell proliferation, making it useful in measuring prognostic indicators in lymphoid neoplasia. The unique attributes of flow cytometry therefore make it a valuable technique in the diagnosis and classification of lymphomas as well as the assessment of prognostic markers in lymphoma patients.

Bone marrow immunohistology of plasma cell neoplasms

The application of immunohistology to the spectrum of plasma cell disorders has yet to be incorporated widely into routine haematology practice. This technique enables the direct visualisation of specific surface and cytoplasmic antigens in the context of the individual cell and the surrounding anatomical neighbourhood. This review outlines the role of bone marrow immunohistology in the laboratory evaluation of patients with suspected and established plasma cell neoplasms and its emerging role in understanding myeloma biology for possible future therapeutic application.

Clonal cytotoxic T cells are expanded in myeloma and reside in the CD8(+)CD57(+)CD28(-) compartment

The occurrence of clonal T cells in multiple myeloma (MM), as defined by the presence of rearrangements in the T-cell receptor (TCR)-beta chains detected on Southern blotting, is associated with an improved prognosis. Recently, with the use of specific anti-TCR-variable-beta (anti-TCRV(beta)) antibodies, the presence in MM patients of expanded populations of T cells expressing particular V(beta) regions was reported. The majority of these T-cell expansions have the phenotype of cytotoxic T cells (CD8(+)CD57(+) and perforin positive). Since V(beta) expansions can result from either a true clonal population or a polyclonal response, the clonality of CD8(+)TCRV(beta)(+) T cells was tested by TCRV(beta) complementarity-determining region 3 length analysis and DNA sequencing of the variable region of the TCR. In this report, the CD57(+) and CD57(-) subpopulations within expanded TCRV(beta)(+)CD8(+) cell populations are compared, and it is demonstrated that the CD57(+) subpopulations are generally monoclonal or biclonal, whereas the corresponding CD57(-) cells are frequently polyclonal. The oligoclonality of CD57(+) expanded CD8(+) T cells but not their CD57(-) counterparts was also observed in age-matched controls, in which the T-cell expansions were mainly CD8(-). The CD8(+)CD57(+) clonal T cells had a low rate of turnover and expressed relatively lower levels of the apoptotic marker CD95 than their CD57(-) counterparts. Taken together, these findings demonstrate that MM is associated with CD57(+)CD8(+) T-cell clones, raising the possibility that the expansion and accumulation of activated clonal CD8(+) T cells in MM may be the result of persistent stimulation by tumor-associated antigens, combined with a reduced cellular death rate secondary to reduced expression of the apoptosis-related molecule CD95.