|Year : 2018 | Volume
| Issue : 3 | Page : 109-114
Signaling lymphocytic activation molecule family-1 (CD150) expression as a prognostic indicator in patients with chronic lymphocytic leukemia
Rasha A Elkholy1, Alzahraa A Allam2
1 Department of Clinical Pathology, Faculty of Medicine, Tanta University, Tanta, Egypt
2 Internal Medicine, Faculty of Medicine, Tanta University, Tanta, Egypt
|Date of Submission||29-Jan-2018|
|Date of Acceptance||25-Mar-2018|
|Date of Web Publication||3-Dec-2018|
Rasha A Elkholy
7 Zaid Ibn Haresah Street, El-Mahalla El-Kubra, 31951
Source of Support: None, Conflict of Interest: None
Introduction Chronic lymphocytic leukemia (CLL) is a common B-cell malignancy characterized by the accumulation of mature monoclonal CD5-positive B-lymphocytes in the peripheral blood, bone marrow, and secondary lymphoid tissues. It is characterized by remarkable clinical variability. CD150 is a multifunctional type I transmembrane glycoprotein; it has been suggested that CD150 expression modulates CLL response to chemokines and regulates autophagy.
Aim The aim of this study was to determine the expression of CD150 in patients with CLL and its relation to the other well-established prognostic markers and also to determine its impact on patient survival.
Patients and methods This case–control study was performed on 50 newly diagnosed CLL patients and 50 apparently healthy individuals as a control group. CD150 expression was measured by flow cytometry.
Results This study has shown that CD150 expression was decreased in CLL patients compared with the control group, with great heterogeneity between CLL patients. There were negative correlations between CD49d, CD38, ZAP-70 expression, clinical staging of CLL patients, and CD150 expression, whereas there were positive correlation between hemoglobin level, platelets count, and CD150 expression. Patients with CD150 expression less than or equal to 6% of CD19-positive B-lymphocytes have shorter progression-free survival and overall survival and needed to start treatment early.
Conclusion CD150 can be a useful tool in identifying B-CLL patient’s risk.
Keywords: CD150, chronic lymphocytic leukemia, signaling lymphocytic activation molecule family-1
|How to cite this article:|
Elkholy RA, Allam AA. Signaling lymphocytic activation molecule family-1 (CD150) expression as a prognostic indicator in patients with chronic lymphocytic leukemia. Egypt J Haematol 2018;43:109-14
|How to cite this URL:|
Elkholy RA, Allam AA. Signaling lymphocytic activation molecule family-1 (CD150) expression as a prognostic indicator in patients with chronic lymphocytic leukemia. Egypt J Haematol [serial online] 2018 [cited 2018 Dec 16];43:109-14. Available from: http://www.ehj.eg.net/text.asp?2018/43/3/109/246778
| Introduction|| |
Chronic lymphocytic leukemia (CLL) is one of the most common chronic lymphoproliferative disorders which is characterized by the presence of at least 5×103/µl monoclonal B-lymphocytes in the peripheral blood with the characteristic phenotype (CD5-positive, CD19-positive, CD23-positive, and weak or negative CD20 expression). These cells accumulate in blood, bone marrow, and lymphoid organs . The most stunning feature of CLL is its clinical heterogeneity with variable overall survival (OS) as some patients can survive many years without any therapeutic intervention and the others have progressive disease which may lead to death rapidly even with treatment. So great efforts were done to identify the impact of the pathophysiological nature of the disease on patients’ prognosis. Positivity of CD38, ZAP-70, CD49d, and lack of somatic hypermutation in the immunoglobulin heavy variable genes have been established as bad prognostic markers .
CD150 family also known as signaling lymphocytic activation molecule family (SLAMF) is a big family which includes nine structurally related leukocyte cell-surface molecule receptors which may play a role in initiation and signaling transduction pathways in numerous cells such as T-lymphocytes, antigen-presenting cells, and natural killer cells ,.
CD150 also known as SLAMF-1 is the first member of SLAM family. It is a multifunctional type I transmembrane glycoprotein, functioning as adhesion and costimulatory molecules, which during the T–B lymphocyte cross-talk acts as self-ligands and regulate the signal transduction pathway that enhances lymphocyte activation . CD150 and other SLAMF receptors show structural homology as they are composed of two immunoglobulin-like domains forming the extracellular domain part: one variable-like lacking disulfide bonds and the other is a truncated immunoglobulin constant 2-like domain with two intradomain disulfide bonds ,. Numerous cells such as activated T-lymphocytes and antigen-presenting cells such as B-lymphocytes, activated monocytes, macrophages, and dendritic cells normally express CD150 ,. Some types of mature B-lymphoproliferative disorders such as Hodgkin’s lymphoma, hairy cell leukemia, and subtypes of diffuse large B-cell lymphoma with activated B-cell phenotype, expressing high levels of CD150 . CD150 might be engaged with the control of microenvironment and pathophysiology of CLL cells .
This study aimed to determine the expression of CD150 in CLL patients and its relation to the other well-established prognostic markers, and to also determine its impact on patients’ survival.
| Patients and methods|| |
The current study was carried out from January 2016 to December 2017 on 50 newly diagnosed patients with CLL and 50 apparently healthy individuals matched in age and sex as the control group. It was carried out according to the Declaration of Helsinki and local ethics committee principles. Informed consent was obtained from patients and the control group.
Inclusion criteria were patients newly diagnosed with CLL. Patients were categorized according to the modified RAI staging system of CLL into three risk groups: low, intermediate, and high.
Exclusion criteria were patients suffering from any malignant diseases other than CLL or CLL and who received treatment.
All patients were asked to enter the study at the time of diagnosis and they were observed for a period of 18 months or until death of the patients, which was considered the endpoint of the study.
Blood collection and laboratory assay
Laboratory assays were performed on peripheral blood obtained from CLL patients. Laboratory investigations including complete blood count using fully automated cell counter (PCE 210N; Erma Inc., Tokyo, Japan), with examination of Giemsa-stained peripheral blood films. Immunophenotyping for CLL diagnosis was performed for all CLL patients, and immunophenotyping to detect the expression of CD150 for patients and the control group was also performed. All flow cytometric analysis were performed on BD FACS Calibur flow cytometer (BD Biosciences, San Diego, California, USA). Monoclonal antibodies used were CD5-FITC, CD19-PE, CD20-APC, CD10-PE, CD2-FITC, CD23-PE, FMC-7-FITC, CD79b-PE, CD38-FITC, ZAP-70-FITC, CD49d-PE, Kappa-FITC, Lambda-PE, and CD150 FITC (Becton Dickinson, Mountain View, California, USA). The leukocytic count was adjusted to 106 cells/tube; flurochrome-conjugated monoclonal antibodies were dispensed into all appropriately labeled tubes (volume of each antibody is determined according to titration which is labeled on each monoclonal bottle). The tubes were vortexed and incubated in the dark at room temperature for 25 min. Lysing solution of 1 ml was added to all tubes. The tubes were vortexed and incubated for 20 min in the dark at room temperature. A volume of 0.5 ml of PBS washing solution was added to each tube and mixed thoroughly. The tubes were centrifuged at 2500 rpm for 3 min, and the supernatant was discarded; this step was repeated. Cells were suspended in 300 µl of PBS and were ready for acquisition by the flow cytometer. As regards ZAP-70, additional step was done by adding 250 µl of fixation and permeabilizing solution for 10 min at room temperature in the dark before adding ZAP-70 monoclonal antibody. A total of 10 000 events (cells) were acquired, from which the lymphocytes were selectively gated for analysis. The cutoff of positivity was 30% for all B-CLL markers except for ZAP-70, which was 20% .
Data were fed to the computer and analyzed using IBM SPSS software package, version 20.0 (Armonk, NY: IBM Corp). Comparison between groups for categorical variables were assessed using χ2-test. Test of univariate normality was using Kolmogorov–Smirnov test and independent t-test was used to compare two groups for normally distributed quantitative variables. Mann–Whitney test was used to compare two groups for abnormally distributed quantitative variables. Kruskal–Wallis test was used to compare different groups for abnormally distributed quantitative variables and was followed by Dunn’s multiple comparisons test for pairwise comparisons. Kaplan–Meier survival curve was used, and Cox regression was done for the significant relation with progression-free survival (PFS) and OS. Spearman’s coefficient was used to correlate between quantitative variables. Significance of the obtained results was judged at a P value less than or equal to 0.05 level .
| Results|| |
A total of 100 participants were included in this study, 50 patients newly diagnosed with CLL, and 50 apparently healthy individuals matched for age and sex as a control group. Clinical characteristics of the patient group are given in [Table 1]. Comparison between CLL patients group and control group as regards laboratory data is provided in [Table 2].
|Table 2 Comparison between chronic lymphocytic leukemia patients group and control group as regards laboratory data|
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There were a statistically significant difference in the percentage of CD150 expression among CD19-positive B-lymphocytes between the control group and the patients group with great heterogeneity in the expression between CLL patients ([Figure 1] and [Figure 2]), as there were a statistically significant difference in CD150 expression between different modified RAI staging. The expression was higher in the low-risk group patients (stage A) compared with intermediate (stage B) and higher in the intermediate compared with the high-risk group (stage C) ([Table 3] and [Figure 3]). To determine the prognostic significance of CD150 expression in CLL, a correlation study was performed between CD150 and other well-established parameters having prognostic values such as age, hemoglobin (Hb) level, platelets count, absolute lymphocytic count (ALC), CD38%, CD49d%, and ZAP-70%. There was no statistically significant correlation between CD150 expression and age of patients, or ALC, whereas there was a statistically significant positive correlation between CD150 expression in the CLL patient group, Hb level, and platelets count. As regards immunophenotypic prognostic markers there was a statistically significant negative correlation between CD150 expression in CLL patients, ZAP-70, CD38, and CD49d expression ([Table 4]). The optimal CD150% cutoff within the CLL population for OS was defined at 6% . Within this study, there were 42 (84%) patients showing CD150 expression of at least 6% and eight (16%) patients with a CD150 expression of less than 6%. Patients with a CD150 expression of at least 6% had significantly longer OS (17.3 vs. 14.5 months) and significantly longer PFS (12.7 vs. 7.1 months) at 18 months compared with those with a CD150 expression of less than 6% ([Figure 4] and [Figure 5]). These results suggest that the CD150 expression is greatly decreased in a subset of CLL patients characterized by an aggressive disease with a shorter PFS and OS.
|Figure 1 Chronic lymphocytic leukemia case with low percentage of CD150 expression.|
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|Figure 2 Chronic lymphocytic leukemia case with high percentage of CD150 expression.|
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|Table 3 Comparison of CD150 expression in different stages of studied chronic lymphocytic leukemia group compared with each other|
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|Figure 3 Comparison between the different studied groups as regards CD150 expression.|
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|Table 4 Correlation between CD150 expression, with age and laboratory findings in the patient group|
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|Figure 4 Kaplan–Meier survival curve for overall survival with CD150 expression.|
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|Figure 5 Kaplan–Meier survival curve for progression-free survival with CD150 expression.|
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| Discussion|| |
CD150 is a multifunctional type I transmembrane glycoprotein that belongs to the SLAM family, which modulates CLL responses to chemokines and regulates autophagy which plays a critical role in removing aggregated proteins and damaged organelles whose accumulation is toxic to the cell ,. So loss of CD150 in CLL cells make them resistant to autophagy and autophagy-inducing drugs, such as B-cell CLL/lymphoma 2 inhibitors . Also dysregulation of SLAMF molecules including CD150 may affect homing and adhesion of CLL cells .
This study was conducted on 100 participants including 50 patients newly diagnosed with CLL of whom 37 (74%) patients were men and 13 (26%) patients were women; their ages ranged from 51 to 77 years with a mean value of 63.65±9.23 and 50 apparently healthy individuals matched for age and sex as a control group. According to the modified RAI staging system, the CLL patients in this study were categorized into three risk groups: the first group included 15 (30%) out of 50 patients with low risk, the second group included 15 (30%) patients with intermediate risk, and the third group included 20 (40%) patients with high risk and this was in contrast with the study by Bosch and Montserrat  who reported that the majority of CLL cases were of low risk, and this may be attributed to its late discovery due to the indolent nature of the disease.
This study showed that the expression of CD150 was decreased in the CLL patients group compared with the control group (P<0.001) with great heterogeneity in the expression between CLL patients, as it ranged from 2.2 to 70% (32.4±18.1). This finding is in concordance with Coma et al. , who reported that the expression of CD150 on B-lymphocytes of CLL patients was significantly lower than its expression on normal mature B cells. Bolonga and colleagues , also revealed that the CLL patients showed highly variable levels of CD150 expression compared with the control group. In this study, there was a statistically significant decrease in the percentage of expression of CD150 in the high-risk patient group in comparison with patients with intermediate or low risk. These results were in accordance with those by Bolonga et al. , who reported that CD150 expression decreased in advanced stages of CLL. Also, nonsignificant correlation was observed between age, ALC, and CD150 expression, whereas there was a statistically significant moderate positive correlation between Hb level, platelets count, and CD150 expression. As regards the prognostic markers, a statistically highly significant negative correlation was present between markers of bad prognosis (ZAP-70, CD49d, CD38) and CD150 expression and this findings was in agreement with the studies of Bolonga et al. , who reported that CD150 expression negatively correlated with CD38 and CD49d expression. To our knowledge, this is the first study which correlates CD150 with ZAP-70 expression, age, or complete blood count data.
Patients with CD150 expression of at least 6% of CD19-positive B-lymphocytes had significantly longer OS (17.3 vs. 14.5 months) and significantly longer PFS (12.7 vs. 7.1 months) at 18 months versus those with CD150 expression of less than 6% of CD19-positive B-lymphocytes and these results were in agreement with those found by Bolonga et al.  who reported that a subset of CLL patients whose CD150% markedly decreased have shorter OS and PFS. These data indicate that CD150 can be used as a surrogate marker for favorable prognosis in CLL as it is maintained in patients with low risk and favorable prognostic markers, whereas it is greatly reduced in patients with advanced disease who have shorter OS and PFS and those patients need starting treatment earlier than their corresponding counter patients, providing the link between expression of CD150 and treatment requirement.
| Conclusion|| |
CD150 can be used as a prognostic marker in CLL patients as it is negatively correlated with poor prognostic markers (CD38, CD49d, ZAP-70) and clinical staging, while positively correlated with Hb level and platelets count. OS and PFS were greatly reduced in a subset of patients with a CD150 expression of less than or equal to 6% of CD19-positive B-lymphocytes.
The authors acknowledge the patients and the nurses of the Internal Medicine and Clinical Pathology Department for their assistance in conducting the study.
Rasha A. Elkholy was responsible for idea selection, laboratory part, review of statistical analysis, and preparation of the manuscript; Alzahraa A. Allam was responsible for selection and follow-up of patients and review of the manuscript.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4]