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Year : 2020  |  Volume : 16  |  Issue : 1  |  Page : 30-33

Interleukin 6 and disease transformation in chronic myeloid leukemia: A Northeast Indian population study

1 Department of Pathology, Banaras Hindu University, Varanasi, Uttar Pradesh, India
2 UGC Advanced Immunodiagnostic Training and Research Centre, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
3 Department of Medicine, Banaras Hindu University, Varanasi, Uttar Pradesh, India
4 Department of Pediatrics, Sir Sundarlal Hospital, Banaras Hindu University, Varanasi, Uttar Pradesh, India
5 Department of Molecular and Human Genetics, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India

Date of Submission08-Feb-2017
Date of Decision15-Aug-2017
Date of Acceptance25-Feb-2018
Date of Web Publication30-Aug-2018

Correspondence Address:
Kavyanjali Sharma
Department of Pathology, Institute of Medical Sciences, Banaras Hindu University, Varanasi . 221 005, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcrt.JCRT_137_17

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 > Abstract 

Background: Interleukin 6 (IL6) has been suggested to be a valuable prognostic marker in chronic myeloid leukemia (CML). IL6 is a pleiotropic cytokine and plays an important role in immune response, hematopoiesis, and acute phase response. IL6 is regarded as a prominent target for clinical interventions.
Objective: The aim of the present study was to investigate the serum levels of IL6 in CML to provide greater insight to their role in disease transformation in Indian patients.
Materials and Methods: A total of 50 CML cases and 10 acute lymphocytic leukemia (ALL) cases along with 20 healthy controls were included in the study between 2015 and 2016. About 4 mL blood samples were collected from all cases in plain vial and serum was separated. Levels of IL6 were determined in all cases by enzyme-linked immunosorbent assay.
Results: The study suggests that both ALL and CML are associated with significantly elevated serum IL6 level than the healthy control group. Mean levels of serum IL6 are 223.4 ± 53.403 pg/mL in CML, 71.020 ± 29.549 pg/mL in ALL, and 5.360 ± 0.467 pg/mL in healthy control group. Serum IL6 correlated with different phases of CML. Mean IL6 levels are 50.93 ± 29.37 pg/mL in chronic phase (CP), 69.02 ± 22.60 pg/mL in accelerated phase (AP), and 652.77 ± 124.62 pg/mL in blast crisis (BC) phase of CML. In compared to CP and AP, in BC, IL-6 is significantly elevated ( P = 0.00 and 0.00, respectively); however, we did not find a significant difference in IL-6 serum levels between CP and AP ( P = 0.703).
Conclusion: Study suggests that the detection of IL6 level in newly diagnosed patient can predict the severity of the disease. There might be association of level of IL6 with the disease transformation.

Keywords: Accelerated phase, acute lymphocytic leukemia, blast crisis, chronic phase, interleukin 6, tyrosine kinase inhibitors

How to cite this article:
Sharma K, Singh U, Rai M, Shukla J, Gupta V, Narayan G, Kumar S. Interleukin 6 and disease transformation in chronic myeloid leukemia: A Northeast Indian population study. J Can Res Ther 2020;16:30-3

How to cite this URL:
Sharma K, Singh U, Rai M, Shukla J, Gupta V, Narayan G, Kumar S. Interleukin 6 and disease transformation in chronic myeloid leukemia: A Northeast Indian population study. J Can Res Ther [serial online] 2020 [cited 2020 Jun 6];16:30-3. Available from: http://www.cancerjournal.net/text.asp?2020/16/1/30/244438

 > Introduction Top

Chronic myelogenous leukemia or chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the increased proliferation of the granulocytic cell line without the loss of their capacity to differentiate. It accounts for 15% of all leukemia affecting adults.[1] CML is consistently associated with the BCR-ABL fusion gene.[2] This abnormal oncoprotein enhances the tyrosine kinase activity of the cells associated with deregulating signaling pathways such as autophosphorylation, JAK/STAT, mitogen-activated protein kinase (MAPK), RAS, RAF, JUN kinase, and MYC responsible for growth.[3] Although it is common among the middle-aged and the elderly person, it may affect children too. It is slightly more common among men than in women. According to the Indian Cooperative Oncology Network in 2010, CML is one of the most common adult leukemia in population accounting for 30%–60% of all adult leukemias. The most common symptom includes splenomegaly ranging from 81% to 100%, followed by hepatomegaly, fatigue, weakness, dragging pain, pallor, or sometimes asymptomatic seen in 30% of cases. In comparison to the Western data, majority of Indian patients are symptomatic with splenomegaly and dull aching pain in the left hypochondriac region.[4]

The WHO has categorized CML into three phases according to its maturation pattern and severity: chronic phase (CP) or stable phase or initial phase (<10% blast), accelerated phase (AP) or progressive phase (10%–19% blast), and blast phase or acute phase or final phase (20 or >20% blast). During blast crisis (BC) phase, the disease transforms into an aggressive, acute leukemia (70% acute myelogenous leukemia and 30% acute lymphocytic leukemia [ALL]). Annual mortality in CML has decreased from 10% to 20% down to 1%–2%.[2],[5]

Nowadays, tyrosine kinase inhibitors (TKIs) that target BCR-ABL are the standard treatment for CML and are being widely used. There are three levels of TKIs used, i.e., first line (Imatinib, Nilotinib, and dasatinib), second line (bosutinib and ponatinib), and third line (ponatinib) of treatment based on the risk of the disease. Mutational analysis is recommended before starting any type of treatment. Early molecular response (EMR) is a strong predictor of outcome in CP-CML patient treated with TKIs.[6] Although TKIs have brought major medical advancement in the treatment of CML, TKIs resistance and disease transformation are still the issues to the treatment of disease. Different mutations have been shown to confer variable degrees of resistance to the TKIs. Other mechanism of resistance is also present there.[7],[8],[9]

There may be a possible role of cytokine environment in EMR failure, early transformation, and BCR-ABL1 kinase mutation. Cytokine profiling showing their importance in CML has been studied by several groups.[10],[11],[12] Among all cytokines, interleukin 6 (IL6) is widely studied by different groups and it is regarded as a prominent target for clinical interventions. IL6 is a pleiotropic cytokine and also known to have hormone-like attributes. It is secreted by all stromal cells and cells of immune system in response to several types of stimuli such as acute phase response, hematopoiesis, and immune reaction.[13] Human IL6 is 20–26 KDa protein and consists of 212 amino acids, including a hydrophobic signal sequence of 28 amino acids. Its gene is situated on chromosome 7p21. It is also known as B-cell stimulatory Factor-2, hepatocyte-stimulating factor, hybridoma growth factor, and interferon beta 2.[14] IL-6 induces signaling through a surface heterodimeric receptor complex (classical signaling) or soluble receptor complex (trans-signaling) composed of a ligand-binding subunit IL-6 receptor alpha and a signal-transducing subunit (gp130).[13] IL-6 is involved in the maintenance of chronic inflammation in many diseases such as cardiac myxoma, rheumatoid arthritis, experimental autoimmune encephalomyelitis, multicentric, Castleman's disease, and pristane-induced lupus and plasmacytomas. Various animal models and other studies showed its pathological role in multiple myeloma, neurological disease, pulmonary fibrosis and hypertension, plasmacytosis, metastasis, and tumor-associated inflammation.[13],[15]

The objective of the present study was to investigate the serum levels of IL6 in CML and ALL and its correlation with different phases of CML and controls.

 > Materials and Methods Top

This study was conducted in the Department of Pathology. All cases were newly diagnosed or first encountered in the outpatient department (OPD), but we have selected those patients who had attended our OPD and directly referred to our laboratory. Fifty CML cases (25 in CP), 11 in AP, 14 in BC phase), 10 ALL cases, and 20 healthy control cases were included in our study. Sample size was determined on the basis of feasibility and availability of the samples during the period of 2015–2016.

All CML cases were collected from medicine OPD and ALL cases were collected from pediatric OPD. Median age for CML patients was 35 years (range: 13–69 years) including 39 male (78%) and 11 female patients (22%). For ALL patients, median age was 7 years (range: 1–14 years) including 7 males (70%) and 3 females (30%). Healthy control group included 14 males (70%) and 6 females (30%) and median age was 41 years (range: 22–64 years). Detailed clinical history including age, sex, peripheral blood count, bone marrow aspiration studies, presence of hepatomegaly and splenomegaly, and karyotyping studies was recorded.

About 4 mL blood samples were collected from the subjects in plain vials after their informed written consent as per the approval of the Institutional Ethical Committee of the Institute of Medical Sciences, Banaras Hindu University. Serum was separated and stored at −80°C until needed.

Level of IL6 was determined in all cases using IL6-enzyme-linked immunosorbent assay (ELISA) Kit (DIAsource immunoassay SA Belgium). It is a quantitative sandwich ELISA kit and test was done according to the manual instruction.

Statistical analysis of the data was done using SPSS Inc. released 2007. SPSS for Windows, Version 16.0.(Chicago, SPSS Inc. USA). The data were analyzed using a two-tailed Student's t -test; P ≤ 0.05 was considered statistically significant.

 > Results Top

In normal healthy control, serum IL6 varied from 2 to 11 pg/mL with a mean of 5.360 ± 0.467 pg/mL. In ALL, 70% patients while in CML 74% patient had elevated value. Mean values of IL6 in CML (223.421 ± 53.403 pg/mL) and in ALL (71.020 ± 29.549 pg/mL) are significantly raised as compared to control, but no significant difference is noted between ALL and CML [Table 1] and [Table 2].
Table 1: Comparison of interleukin 6 values between different groups of patients

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Table 2: Comparison of interleukin 6 value between different groups of patients

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Correlation of IL6 with different phases of CML revealed that mean value is highest in BC phase, followed by AP and CP [Figure 1]. Rise of IL-6 in BC phase is statistically significant in comparison to CP and AP, but no significant difference is found between CP and AP [Table 3].
Figure 1: Level of interleukin 6 is raised in CML and acute lymphocytic leukemia in comparison to control group. Blast crisis phase of CML shows the highest level of interleukin 6 in comparison to other phases, acute lymphocytic leukemia, and control group

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Table 3: Comparison of interleukin 6 value between three phases of chronic myeloid leukemia

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 > Discussion Top

The study shows that ALL and CML both are associated with elevated IL6 level. Furthermore, distinctive pattern of serum IL6 is present in different phases of CML. The highest level of IL6 was found in the BC phase of CML, suggestive of dysregulation of IL6 may be associated with transformation of CML in BC.

Similar results have been reported by different groups as well. One of the studies showed that high level of IL-6 had been associated with BC phase of CML, which had been significantly correlated with peripheral blood monocyte counts and bone marrow blast and basophil counts. Thus, IL6 may be responsible for some of the abnormalities of BC phase of CML.[16] Similar study was reported by Zhara et al . in 2007.[17] Other studies showed that, in CP, some stimuli are responsible for consistent IL6 production, resulting in increased proliferation and secondary abnormalities in BC.[18] One report suggested that IL6 is a novel biomarker for CML. High value of plasma IL6 level had been associated with transformation to BC and reduced event-free survival. This also predicts failure to achieve EMR and molecular response.[12] IL-6 has been demonstrated to directly stimulate proliferation of tumor cells and promote angiogenesis. Several reports have found that IL-6 levels correlate with disease progression and inversely correlate with response to treatment and survival.[19]

To understand pathophysiology of IL6 in CML, several studies have been conducted by different groups. IL-6 is responsible for myeloid expansion and lymphocytopenia.[20] One of the studies showed that division and expansion of CD34+ progenitor cells is caused by CML cells, and this process depends on IL6 cytokine and hence IL6 promotes the disease.[11] Using mouse model, it has been shown that IL6 is produced by elevated myeloid CML cells which then act on multipotent progenitor cells and transform their BCR/ABL-driven intrinsic B cell potential toward myeloid lineage. By blocking this IL6, CML onset situation can be delayed in spite of active BCR/ABL. Later, fusion gene controls IL6 expression involving BCL6 and LIN28/28b, thus establishing a paracrine loop.[21] Several studies have been made in the search of IL6 inhibitors which can be used in the treatment of CML along with TKI. These inhibitors target molecular signals involved in IL6 pathway. JAK-STAT and MAPK pathways of IL6 are involved in CML.[22] IL6 makes a complex with IL6 receptor on plasma membrane present on target cells and gp130 molecule. This fully functional IL6 receptor complex signaling leads to the activation of Jak1, Jak2, and Tyk2, ultimately activating STAT1, STAT3, and the MAPK.[13] Phosphorylation of STAT3 has an important role in signaling process of JAK/STAT and MAPK pathway; hence, it is a crucial target for IL6 inhibition.[22]

Chen et al . reported that targeting BCR ABL and JAK2 activities together in CML may improve outcome in patients destined to develop imatinib mesylate (IM) resistance. The WD40-repeat domain of Abelson helper integration site 1 interacts with BCR-ABL, whereas the N-terminal region interacts with JAK2. By disruption in these interactions, IM sensitivity of CML cells can be increased.[23]

 > Conclusion Top

Detection of IL6 in a newly diagnosed patient may predict severity of disease and treatment outcome; thus, IL6 acts as a prognostic marker. Disease persistence, relapse, and insensitivity or resistance to drugs in CML may be associated with high IL6 level. Although inhibitors of IL6 cannot alone prevent the disease but together with TKI, it can improve the treatment outcome. However, more studies are required to clear the exact role and also IL6 inhibitor study should be done for the betterment of CML treatment.


We are thankful to Miss Shailja Singh for her technical support.

Financial support and sponsorship

We are thankful to the UGC Advanced Imunodiagnostic Training and Research Centre (UGC AITRC) and Indian Council of Medical Research (ICMR), New Delhi for financial support.

Conflicts of interest

There are no conflicts of interest.

 > References Top

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Vardiman JW. The World Health Organization (WHO) classification of tumors of the hematopoietic and lymphoid tissues: An overview with emphasis on the myeloid neoplasms. Chem Biol Interact 2010;184:16-20.  Back to cited text no. 2
Bartram CR, de Klein A, Hagemeijer A, van Agthoven T, Geurts van Kessel A, Bootsma D, et al. Translocation of c-ab1 oncogene correlates with the presence of a Philadelphia chromosome in chronic myelocytic leukaemia. Nature 1983;306:277-80.  Back to cited text no. 3
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Soverini S, Hochhaus A, Nicolini FE, Gruber F, Lange T, Saglio G, et al. BCR-ABL kinase domain mutation analysis in chronic myeloid leukemia patients treated with tyrosine kinase inhibitors: Recommendations from an expert panel on behalf of European leukemiaNet. Blood 2011;118:1208-15.  Back to cited text no. 9
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Hunter CA, Jones SA. IL-6 as a keystone cytokine in health and disease. Nat Immunol 2015;16:448-57.  Back to cited text no. 13
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Zhara M, Mourad H, Farouk G, Elbatch M, Ezzat S, Sami W, et al. Molecular detection of survivin expression, antiapoptotic gene, and other prognostic markers, how they are correlated and how it could be of prognostic value in chronic myeloid leukemia patient. Egypt J Immunol 2007;14:51-62.  Back to cited text no. 17
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  [Figure 1]

  [Table 1], [Table 2], [Table 3]


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