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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 44  |  Issue : 1  |  Page : 54-64

Improperly functioning phagocytic cells contribute to disturbed phagocytosis in chronic lymphocytic leukaemia


1 Department of Clinical Pathology, Faculty of Medicine, Alexandria University Hospitals, Alexandria, Egypt
2 Hematology Unit, Department of Internal Medicine, Faculty of Medicine, Alexandria University Hospitals, Alexandria, Egypt

Date of Submission02-May-2018
Date of Acceptance27-Jun-2018
Date of Web Publication27-Sep-2019

Correspondence Address:
Amira I Fayad
Department of Clinical Pathology, Faculty of Medicine, Alexandria University Hospitals, Al Khartoum Square, El Azareta, Alexandria, 21526
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ejh.ejh_19_18

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  Abstract 


Background Patients with chronic lymphocytic leukaemia (CLL) are endangered by fatal infectious complications. CLL cells shape their surrounding microenvironment as immune effectors which manifests as tolerance mechanisms, avoiding self-reactivity and inhibiting phagocytosis. Immune-therapeutic approaches tailoring antitumor potentials of phagocytic cells have been the focus of recent studies.
Aim To study whether examining phagocytic cells’ functional status in patients with CLL can provide insights into immune system deregulation responsible for fatal infectious complications.
Patients and methods The study was conducted on patients with CLL: 30 de-novo (group IA), 30 treated (group IB), and 20 healthy age-matched and sex-matched volunteers. Phagocytosis by neutrophils and monocytes was studied using phagotest kit, assayed as percentage of cells ingesting FITC-Escherichia coli, and phagocytosis mean fluorescence intensity (MFI), representing individual cellular phagocytic activity. Phagocytic activity was correlated with corresponding leukocytes CD47 surface expression levels.
Results There was a decreased percentage of neutrophils and monocytes ingesting bacteria in subgroup IA or IB compared with group II (P=0.043 and 0.015, respectively). Phagocytosis MFI by neutrophils or monocytes in subgroup IA or IB was lower than control group. There was increased CD47 surface expression by lymphocytes, neutrophils, and monocytes at the time of diagnosis, which decreased as the disease progressed; however, it was still higher than the control group. Paradoxical correlation was detected between CD47 surface expression levels and phagocytosis MFI by neutrophils or monocytes (r2=0.606, P=0.02, and r2=−0.419, P=0.6, respectively).
Conclusion In CLL, phagocytic cells were improperly functioning and the percentage of functioning cells was decreased. CD47 expression levels by leukocytes varied throughout the course of the disease, reflecting disease progression and paradoxically correlated with phagocytic function.

Keywords: CD47, chronic lymphocytic leukaemia, immune deregulation, phagocytosis


How to cite this article:
AbouSeif M, El-Sorady M, Fayad AI, El-Lakany OF. Improperly functioning phagocytic cells contribute to disturbed phagocytosis in chronic lymphocytic leukaemia. Egypt J Haematol 2019;44:54-64

How to cite this URL:
AbouSeif M, El-Sorady M, Fayad AI, El-Lakany OF. Improperly functioning phagocytic cells contribute to disturbed phagocytosis in chronic lymphocytic leukaemia. Egypt J Haematol [serial online] 2019 [cited 2019 Oct 23];44:54-64. Available from: http://www.ehj.eg.net/text.asp?2019/44/1/54/267999




  Introduction Top


Patients with chronic lymphocytic leukaemia (CLL) are at an increasing danger of infectious complications, which are responsible for reported morbidity and mortality [1],[2],[3]. Predisposition to infections in patients with CLL is either owing to a primary defect in the immune response related to stage and duration of CLL [4],[5] or secondary to the used chemo-therapeutic regimens [6]. In CLL, defect in immune system is multifactorial [7],[8],[9]: humoral-mediated immune responses as hypogammaglobulinemia [10], or cellular mediated, such as defects in immune-effector cells, including T cells [11],[12], natural killer (NK) cells [13], neutrophils [14] or monocyte/macrophage lineage [15]. Additionally, chemotherapy-induced defects to adaptive cellular immunity predispose patients to life-threatening infections.

Pathophysiology of CLL and the role of chronic inflammation in the initiation and progression of CLL need more unveiling, which entails the importance of expansion the study of the composition and function of CLL-associated myeloid cells [16].

Neutrophils, the most abundant phagocytes in the circulation, are integrated in innate defense against infection [17] and mediate antibody-dependent cell cytotoxicity [18]. In CLL, neutrophil dysfunction represented as impaired bactericidal activity [19] or differentiate toward a B-cell helper phenotype in murine model of CLL developing survival niches for CLL cells in lymph nodes [20]. The role played by neutrophils in CLL treatment was highlighted in demonstrating neutrophils contribution in clearing 47% of glycoengineered anti-CD20 (obinutuzumab) opsonized CLL targets, augmenting the treatment response [21].

Monocytes, precursors of resident macrophages, are important cells in the dialogue between inflammatory response and cancer development. Monocytes’ role in CLL pathogenesis and how tumor cells modulate the functions of monocytes promoting tumor progression have been addressed [15]. Immune-therapeutic approaches, based on the ability of therapeutic antibodies to mobilize antitumor potential of phagocytic cells, have been the focus of many studies [22],[23]. These approaches are considered as strategic line of treatment in CLL and other malignancies.

In an attempt to understand how phagocytic cells function in CLL, we studied the phenotypic and functional properties of circulating neutrophils and monocytes from patients with CLL at diagnosis and after treatment. The correlation of phagocytic activity with CD47 surface expression by leukocytes, as CD47 plays a critical role in mediating the phagocytic response was addressed [24],[25],[26].


  Patients and methods Top


Patients

This study was carried out on 50 patients. They were classified into two groups. Group I included 30 patients diagnosed with CLL (diagnosed as 5000/μl lymphocytes expressing CD5, CD20, and CD23). B-CLL patients comprised 14 males and six females, with age range from 41 to 73 years. The study was approved by the medical ethics committee, and informed consents were obtained from the patients to participate in the study.

Group I was subdivided into two subgroups: subgroup IA, at initial diagnosis (n=30), and subgroup IB, following treatment (n=30) at the Hematology Unit, Alexandria University Hospital. Group II included 20 healthy age-matched and sex-matched volunteers as a control group, comprising 10 males and 10 females, with age ranged from 45 to 72 years. All studied cases were clinically free of liver diseases, diabetes mellitus, and renal diseases.

The studied patients were those admitted to the Hematology Unit, Internal Medicine Department, Faculty of Medicine, Alexandria University Hospitals.

Complete blood count

Blood samples were obtained from all participants in K2-EDTA vacutainer blood collection tubes. Complete blood counts were performed on an automated cell counter ADVIA 2120 (SIEMENS, SPSS VERSION 20, IBM, Version 20.0, Armonk, NY: IBM Corp.) haematology system. Peripheral blood (PB) smears were stained by Leishman’s stain and microscopically examined to assess differential blood cell counts, absolute lymphocytic count, and the morphological characteristics of lymphoid cells [27].

Serum immunoglobulins assay (IgG and IgM)

Venous blood was withdrawn in plain red topped vacutainer tubes for measurement of immunoglobulins (IgG and IgM). These tests were performed by the BN ProSpec System applying nephelometric principle [28], with IgM reference range of 0.4–2.2 g/l and IgG reference range of 7–16 g/l.

Immunophenotying

EDTA anticoagulated PB was used and cells were stained for surface markers using monoclonal antibodies for diagnosis CLL using scoring system: CD5, CD19, CD22, CD23, FMC7, κ and λ [29],[30]. Acquisition and analysis of the data was done using BD, FACS Calibur flow cytometer equipped with BD CellQuest Pro software (BD Biosciences, San Jose, California, USA). For staining of intracellular markers, 4% paraformaldehyde was added to the cells and incubated before staining.

Phagotest

Phagocytosis was assessed using phagotest kit (lot 16420; Glycotope Biotechnology, GmbH, Heidelberg, Germany). Cells were stained according to manufacturer, and 2×104 cells per sample were analysed within 60 min by flowcytometry using FL1 to detect phagocytosis of FITC- Escherichia More Details coli. DNA staining of cells was done to exclude bacteria aggregates, which had the same scatter light properties as leukocytes. Overall, 2×104 leukocytes per sample were analyzed by flow cytometry using FL2 fluorescence channel. The percentage of phagocytes (neutrophils or monocytes) performed phagocytosis was analyzed as well as their mean fluorescence intensity (MFI), which reflected the average number of ingested bacteria per individual cell.

CD47 expression

Cells were stained by CD47-PE, human (clone: REA220; Immunostep) and CD19-FITC, human (clone: LT19; Immunostep, Avda. Universidad de Coimba, Cancer Research Center, Campus Miguel de Unamuno, Spain, www.immunostep.com). Gating for targeted cell population was done according to its size and granularity. The studied populations were defined as follows: R1 represented lymphocyte population (CD19+CD47+), R2 represented the granulocytic population (neutrophils) (CD19CD47+) and R3 represented monocytic population (CD19CD47+) ([Figure 1]). The data were reported as percentage of gated population and MFI of CD47 expression on selected population.
Figure 1 Dot plot shows gates used to identify cell population. The studied populations were gated according to size and granularity and distributed across forward scattered (FSC) and side scattered (SSC). The gates were defined as R1, R2 and R3, where R1 (red colour) represented lymphocyte population, R2 (green colour) represented granulocyte population, and R3 (purple colour) represented the monocyte population.

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Statistical analysis of the data

Data were fed to the computer and analysed using IBM SPSS software package version 20.0. Qualitative data were described using number and percentage. Quantitative data were described using range (minimum and maximum), mean, SD and median. Significance of the obtained results was judged at the 5% level. The tests used were χ2-test used for categorical variables, to compare between different groups. Mann–Whitney test was used for abnormally quantitative variables, to compare between two studied groups. Kruskal–Wallis test was used for abnormally quantitative variables, to compare between more than two studied groups. Spearman coefficient was used to correlate between two abnormally quantitative variables.


  Results Top


Studied cases

This study was carried out on 30 patients with CLL (group I) who were subdivided into two subgroups: subgroup A, newly diagnosed, and subgroup B, following treatment. Scoring of patients in subgroup IA showed that 22 (73.3%) patients had score 5/5, six (20%) patients had score 4/5 and two (6.7%) patients had score 3/5. Descriptive analysis of the demographic, clinical examination, and laboratory characteristics of the studied patients is shown in [Table 1] and [Table 2]. The study showed hypogammaglobulinemia in patients with CLL in which subgroup IA showed 80% of patients had IgM level below normal level with values ranging 0.1–0.39 g/l, and 46.7% had IgG below normal levels, ranging from 2.90 to 6.99. In subgroup IB, 46.7% of patients had IgM level below normal levels, ranging from 0.1 to 0.3 g/l, and 46.7% had IgG below normal levels ranging from 2.9 to 5.8 g/l. Hypogammaglobulinemia (IgM and IgG) in patients with CLL showed statistical significant difference compared with control group (P<0.001 and P=0.028, respectively).
Table 1 Characteristics of studied groups: demography, immunoglobulin serum levels, and clinical examination

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Table 2 Characteristics of the studied groups: peripheral blood picture

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Decreased percentage of phagocytes in patients with chronic lymphocytic leukaemia

In the context of assessing immune status, phagocytosis by phagocytes (neutrophils and monocytes) was studied in cases and control participants using phagotest kit. Bacterial aggregates were excluded before analysing the data by performing DNA staining, and leucocyte DNA was expressed as a single peak, with MFI ranging from 3000 to 10 000, with a mean of 6000 ([Figure 2]a).
Figure 2 Phagocytosis by neutrophils and monocytes in chronic lymphocytic leukaemia; (a) leukocyte DNA was stained and analyzed by flowcytometry using FL2. DNA signal was expressed as single peak with mean fluorescence intensity (MFI) 6000. Phagocytosis by (b) neutrophils or (c) monocytes was analysed by flow cytometry using FL1; histogram for 0°C sample (green colour), at 37°C for 10 min (blue colour). (d) Histogram shows phagocytosis cell percentage (right) and phagocytosis MFI (left) by neutrophils and monocytes. Data are represented as mean±SD. *Statistical significance difference. IA=newly diagnosed, IB=treated, II=control group. **Moderately significant. ***Highly significant.

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Phagocytosis by neutrophils

Neutrophils were gated according to size and granularity, and phagocytosis was studied at 0 and 37°C. In subgroup IA, phagocytizing neutrophils percentage ranged from 30 to 94% (mean 71.87±10.01) of total neutrophils and phagocytosis MFI ranged from 1070 to 3252 (mean 1859±409) ([Figure 2]b and [Table 3]). In subgroup IB, phagocytizing neutrophils percentage ranged from 45 to 94% (mean 72.2±14.3) of total neutrophils and phagocytosis MFI ranged from 1000 to 2991 (mean of 1586±592) ([Figure 2]b and [Table 3]). In control group (group II), phagocytizing neutrophils percentage ranged from 75 to 95% (mean 86.40±7.7) of total neutrophils and phagocytosis MFI ranged from 1443 to 4332 (mean 2589±932) ([Figure 2]b and [Table 3]). Phagocytizing neutrophils percentage in subgroup IA or IB was less than control group, with statistically significant difference (P=0.043 and 0.015, respectively). Phagocytosis MFI showed trend of having lower MFI in subgroup IA or subgroup IB compared with control group (group II), reflecting less number of bacteria ingestion; however, no statistical significance was detected.
Table 3 Phagocytic function by neutrophils or monocytes represented as cell percentage and phagocytosis mean fluorescence intensity in the studied groups

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Phagocytosis by monocytes

Monocytes were studied using the same protocol applied to study phagocytosis by neutrophils, except for the monocytes gating settings. In subgroup IA, phagocytizing monocytes percentage ranged from 30 to 75% (mean 52±5.6%) of the total monocytes and phagocytosis MFI ranged from 416 to 3531 (mean 1981±400) ([Figure 2]c and [Table 3]). In subgroup IB, percentage of phagocytizing monocytes ranged from 40 to 91% (mean 63.4±13%) and phagocytosis MFI ranged from 1000 to 3921 (mean 1986±600) ([Figure 2]c and [Table 3]). In the control group (group II), phagocytizing monocytes percentage ranged from 40 to 92% (mean 68.9±16%) and phagocytosis MFI ranged from 1583 to 6084 (mean 2972±802) ([Figure 2]c and [Table 3]). The data showed that phagocytizing monocytes percentage was lower in subgroup IA or IB compared with control group, but it did not show statistically significant difference. Phagocytosis MFI was lower in subgroup IA or IB, reflecting less ingested bacteria when compared with control group, but no statistical significant difference was detected.

Increased CD47 surface expression by leukocytes in patients with chronic lymphocytic leukaemia

CD47 surface expressions by lymphocytes, neutrophils and monocytes were studied in which 4×105 cells from all studied participants were stained by PE-CD47 and FITC-CD19 mAbs, and the studied populations were defined as R1, R2 and R3 (described in ‘Patients and methods’ section).

The data for CD47+CD19+ B-lymphocytes in gate R1 are shown in [Figure 3]a and [Table 4]. In subgroup IA, CD47+CD19+ lymphocytes percentage ranged from 58 to 96% (mean 85±9.3%) and CD47 MFI ranged from 402 to 1977 (mean 902±200). In subgroup IB, CD47+CD19+ lymphocytes percentage ranged from 5 to 41% (mean 19.70±12%), and CD47 MFI ranged from 300 to 962 (mean 491±167). In group II, CD47+CD19+ lymphocytes percentage ranged from 4 to 16% (mean 9.7±3.8%), and CD47 MFI ranged from 313 to 1025 (mean 526±238). The data showed that in subgroup IA, CD47+CD19+ lymphocytes percentage was higher than both subgroup IB and group II with statistically significant difference (P<0.001 and 0.001, respectively), and CD47 MFI in subgroup IA was higher than both subgroup IB or group II, with statistically significant difference (P=0.001 and 0.023, respectively). As for subgroup IB, CD47+CD19+ lymphocytes percentage was higher than group II, with statistically significant difference (P=0.023), and CD47 MFI was higher than group II, with no statistical significance.
Figure 3 CD47 surface expression in patients with chronic lymphocytic leukaemia. 4×105 cells were stained with PE-CD47 and FITC-CD19 mAbs. The studied populations were defined as R1, R2 and R3 (‘Patients and methods’ section). (a) B-lymphocytes (R1) expressing CD47+CD19+ as dot plot in the upper right quadrant, (b) neutrophils (R2) expressing CD47+CD19 in the upper left quadrant, (c) monocytes (R3) with CD47+CD19 in the upper left quadrant, events were captured and analyzed by flow cytometry for subgroup IA; newly diagnosed, IB; treated patients, control participants. Dot plot is representative to one of the studied cases. (d) Histograms represent cells percentage (right) and CD47 mean fluorescence intensity (left) as mean±SD. *Statistical significance difference.

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Table 4 CD47 surface expression by leukocytes in patients with chronic lymphocytic leukaemia

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The data for CD47+CD19 neutrophils in gate R2 are shown in [Figure 3]b and [Table 3]. In subgroup IA, CD47+CD19 neutrophils percentage ranged from 66 to 96% (mean 87±9) and CD47 MFI ranged from 176 to 747 (mean 417±165). In subgroup IB, CD47+CD19 neutrophils percentage ranged from 74 to 99% (mean 91.5±6.8%) and CD47 MFI ranged from 128 to 698 (mean 317±157). In group II, CD47+CD19 neutrophils percentage ranged from 82 to 97% (mean 91.2±5%), and CD47 MFI expression ranged from 119 to 405 (mean 232±93). The readings showed no statistical difference in CD47+CD19 neutrophils percentage between groups, but CD47 surface expression MFI showed trend of increase in subgroup IA and decreased in subgroup IB but was still higher than control group, with no statistically significant difference.

The data for CD47+CD19 monocytes in gate R3 are shown in [Figure 3] and [Table 3]. In subgroup IA, CD47+CD19 monocytes percentage ranged from 50 to 90% (mean 68±14.4%) and CD47 MFI ranged from 500 to 850 (mean 700±126). In subgroup IB, CD47+CD19 monocytes percentage ranged from 81 to 86% (mean 83.5±2%) and CD47 MFI expression ranged from 394 to 725 (mean 556±109). In group II, CD47+CD19 monocytes percentage ranged from 82 to 90% (mean 86±3.2%) and CD47 MFI expression ranged from 250 to 955 (mean 426±280). CD47+CD19 monocytes percentage was less in subgroup IA compared with subgroup IB or control, with statistically significant difference (P=0.023 and 0.011, respectively). However, CD47 surface expression MFI showed a trend of increase in subgroup IA and decreased in subgroup IB, but it was still higher than control group, with no statistically significant difference.

Paradoxical correlation between CD47 surface expression levels and phagocytic function

CD47 plays a key role in mediating cellular phagocytic response, so we attempted to study the correlation between CD47 surface expression levels by neutrophils or monocytes with phagocytosis MFI by the corresponding cell population in subgroups IA and IB. Neutrophils showed in subgroup IA statistically significant positive correlation between CD47 surface expression levels and phagocytosis MFI (r2=0.606, P=0.022). In subgroup IB, the positive correlation was preserved, although not statistically significant (r2=0.407, P=0.704) ([Table 5]). Interesting, monocytes showed reversed phenomena, as there was a trend of inversed correlation between CD47 expression and phagocytosis MFI, as in subgroup IA, the correlation was r2=−0.514, P=0.645, and in subgroup IB r2=−0.371, P=0.468, with no statistical significance ([Table 4]).
Table 5 Correlation between CD47 surface expression and phagocytosis mean fluorescence intensity

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  Discussion Top


Disturbed functional status of phagocytic cells in patients with CLL at the time of diagnosis and following treatment presented as improperly functioning cells might contribute to diminished immune status and efficacy of used therapeutic antibodies. In addition, CD47 surface expression by leukocytes, which was lately considered as an important hallmark of phagocytosis, varied through the course of CLL, reflecting disease progression and paradoxically correlated with phagocytic function.

Phagocytosis by neutrophils and monocytes constitutes an essential arm of host defense against bacterial or fungal infections. Our study focused on assessing the phagocytosis status of neutrophils and monocytes in patients with CLL, which showed decreased in number of functioning cells in patients with CLL at diagnosis as well as after treatment compared with age-matched healthy persons. Additionally, neutrophils and monocytes were functionally ineffective as they showed decrease phagocytosis MFI, reflecting decreased number of ingested FITC-E. coli per individual cell in patients at time of diagnosis and after treatment. This quantitative as well as qualitative defect in phagocytic cells could help in explaining the dysfunctional immune status experienced in patients with CLL.

Our study agreed with the study by Gabunia et al. [31] on the phagocytic function of granulocytes in CLL using Staphylococcus aureus opsonized with rabbit polyclonal IgG antibodies and added to polymorphonuclear neutrophils (PMNs) previously isolated on double ficoll gradient. The numbers of PMNs with internalized and/or attached opsonized bacteria were evaluated per 200 PMNs. The study showed that attachment of the opsonized particles was similar to that in controls; however, there was a significant decrease in internalization by PMNs. On the contrary, Itala et al. [4] studied the phagocytic function of granulocytes in CLL using preopsonized S. aureus bacteria. They showed that mean percentage of phagocytosed bacteria was normal in patients with CLL as compared with the control group; however, they studied only the total number of bacteria ingested by granulocytes but could not evaluate the percentage of granulocytes which ingested the bacteria and number of bacteria ingested per cell [4],[11].

Improperly functioning granulocytes and monocytes in patients with CLL shown in this study could be resulted from the primary disease or release of inhibitory chemokine by malignant B cells affecting phagocytosis [16] or physical hindrance preventing proper cell–cell contact resulting from marked increase in B-CLL absolute leukocytic count [29]. Our study showed negative correlation between absolute lymphocytic count with neutrophils or monocytes percentage and phagocytosis MFI in which lymphocytosis was associated with decrease in percentage of phagocytizing cells and MFI; however, it did not reach statistical significance (data not shown).

Dysfunction of monocytes was also reported by the study by Jurado-Camino et al. [32], which demonstrated that in patients with CLL, monocytes were locked into a refractory state and exhibited primary features of endotoxin tolerance where monocytes were unable to mount a classic inflammatory response. Comparable study showed neutrophil dysfunction in patients with CLL which failed to respond adequately to LPS stimulation and showed increased activated markers such as CD64 and CD54 with suppressed functionality [33]. The reported dysfunction of phagocytes in patients with CLL highlights the importance of understanding the role they play in the pathogenesis of CLL, and the relatively high rate of infectious complications in patients with CLL could be the result of an inefficient immune response.

To gain more insights on the phenotype of circulating phagocytes in CLL, we studied the expression of CD47 by different cell lineages and correlated it with the phagocytic functions. Our study showed trend of increased CD47 surface expression by lymphocytes, neutrophils, and monocytes at time of diagnosis, which decreased as disease progress, but was still higher than control group. Lymphocytes showed marked increase of percentage of cells expressing CD47 as well as CD47 surface expression MFI compared with those who received treatment or healthy donors, with statistically significant difference. The detected increase of CD47 by lymphocytes has been highlighted and explained in term of tumor strategy to escape phagocytosis. It can be explained as the B-CLL cells may upregulate CD47 to escape innate immune system surveillance by inhibition of phagocytosis through interaction with SIRPα on the macrophages [25],[34]. The same pattern of CD47 expression was detected by neutrophils and monocytes, as CD47 expression MFI was higher at time of diagnosis and decreased after treatment, with levels higher than control groups. The increase of CD47 expression by neutrophil might help in prolonging their lifespan and delaying their phagocytosis by macrophages. Similar neutrophil phenotype was detected in solid tumor and non-small-cell lung cancer [35], as the study showed that increase in CD47 expression delayed neutrophil clearance by monocyte and explained the detected neutrophilia.

Interestingly, paradoxical correlation was detected between CD47 surface expression levels and phagocytosis MFI in neutrophils and monocytes, as our study of neutrophils showed in subgroup IA statistical significant positive correlation between CD47 surface expression levels and phagocytosis MFI (r2=0.606, P=0.022), and in subgroup IB, the positive correlation was preserved, although not statistical significant (r2=0.407, P=0.704). Interesting, monocytes showed reversed phenomena, as there was a trend of inversed correlation between CD47 expression and phagocytic activity, where in subgroup IA, the correlation was r2=−0.514, P=0.645, and in subgroup IB r2=−0.371, P=0.468, with no statistical significance. CD47 upregulation by monocytes is believed to be a part of disease strategy to attenuate monocytes function, as our study detected a moderate negative correlation. Several publications have suggested that ligation of CD47 inhibited macrophage and dendritic cell cytokine synthesis [36],[37]. We hypothesized that by undermining neutrophil clearance through a decrease in monocytes phagocytic function, as one of important antigen presenting cell, might help in escaping of tumor from immune surveillance. A recent study showed that staphylococcus aureus Scientific Name Search  modulated human immune system through a similar mechanism, surviving within PMN and undermining the innate immune response [38].

CLL is characterized by apoptosis resistance and dysfunctional immune response. Several studies addressed the role played by myeloid cells in causing these defects. Nevertheless, the behavior of CLL-associated myeloid cells needs further insights. We believe that the paradoxical deregulation of the immune system concluded in our study might help in understanding the paradigm of co-occurrence of an increased inflammatory response to minor insult with an inadequate response to infectious stimuli, a picture frequently experienced in patients with CLL. Targeting non-malignant myeloid cells as a new immune therapeutic approach may convey a new vision for approaching patients with CLL.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

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