|Year : 2022 | Volume
| Issue : 1 | Page : 76-80
Spectrum of immunophenotypic aberrancies in acute leukemia along with their correlation with adverse hematological parameters
Sana Ahuja, Avneesh Malviya
Department of Pathology, Shri Guru Ram Rai Institute of Medical and Health Sciences, Dehradun, Uttarakhand, India
|Date of Submission||17-Jun-2021|
|Date of Acceptance||28-Sep-2021|
|Date of Web Publication||24-Jan-2022|
Dr. Sana Ahuja
4 Old Survey Road, Dehradun, Dehradun, Uttarakhand
Source of Support: None, Conflict of Interest: None
BACKGROUND: The identification of aberrant phenotypes in acute leukemia is crucial for treatment monitoring and minimal residual disease analysis. Flowcytometric immunophenotyping in acute leukemia is an important tool for the detection of these aberrancies. There is wide variation in the incidence of aberrant antigens in acute leukemia in different studies and its correlation with prognostic markers.
AIMS AND OBJECTIVES: The aim and objective of this study is to assess the frequency of aberrant markers in acute leukemia and determine any association with hematological parameters.
MATERIALS AND METHODS: A total of 150 newly diagnosed cases of acute leukemia during the period January 2018–December 2020 were included. The flowcytometric immunophenotyping of all the above cases was done using BD FACS Canto II.
RESULTS: Out of the total 150 cases of acute leukemia, 56.7% expressed aberrant phenotype. The proportional frequency of aberrant antigen expression in B-acute lymphoid leukemia (ALL), T-ALL and acute myeloid leukemia (AML) was 56.6%, 50%, and 58.5%, respectively. CD13, CD13, and CD7 were the most common aberrancies in B-ALL, T-ALL, and AML, respectively. Aberrant myeloid phenotype in B-ALL was associated with lower mean total leukocyte count (TLC) and blast percentage in peripheral blood as compared to the B-ALL with conventional phenotypes. Aberrant lymphoid phenotype in AML was associated with a higher TLC and greater blast percentage in peripheral blood than the AML with conventional phenotypes.
CONCLUSION: Aberrant lymphoid phenotype in AML is associated with unfavorable hematological features. However, aberrant myeloid phenotype in B-ALL is not associated with adverse features.
Keywords: Aberrant, flowcytometry, leukemia, lymphoid, myeloid, phenotype
|How to cite this article:|
Ahuja S, Malviya A. Spectrum of immunophenotypic aberrancies in acute leukemia along with their correlation with adverse hematological parameters. Indian J Health Sci Biomed Res 2022;15:76-80
|How to cite this URL:|
Ahuja S, Malviya A. Spectrum of immunophenotypic aberrancies in acute leukemia along with their correlation with adverse hematological parameters. Indian J Health Sci Biomed Res [serial online] 2022 [cited 2022 May 22];15:76-80. Available from: https://www.ijournalhs.org/text.asp?2022/15/1/76/336295
| Introduction|| |
Acute leukemia is a heterogeneous group of hematological malignancies with clonal expansion of neoplastic myeloid/lymphoid cells in blood and bone marrow. They display variation in clinical, morphological, cytochemical, immunophenotypic, and molecular features between acute myeloid leukemia (AML) and acute lymphoid leukemia (B-ALL and T-ALL).
The blast cells in acute leukemia display the characteristic pattern of surface antigen expression called as cluster of differentiation (CD) antigens. These markers form the basis of the current classification of hematological malignancies into different types.
However, some leukemias demonstrate blast cells which do not exhibit the markers of normal cellular differentiation and maturation called aberrant immunophenotype. The B/T-ALL may express myeloid antigens and vice versa.
This possibly results from abnormal genetic programming leading to precursor cells retaining features of one lineage, which should have been lost during differentiation to another lineage.
Flowcytometric immunophenotyping plays an important role in the identification of lineage of acute leukemia along with the detection of aberrant antigens, which help in treatment monitoring and minimal residual disease (MRD) analysis.
The present study aims at assessing the frequency of aberrant expression of CD markers in acute leukemia and determine any association with hematological parameters.
| Materials and Methods|| |
This is a retrospective study conducted on all newly diagnosed consecutive cases of acute leukemia from January 2018 to December 2020 after ethical clearance was obtained from Institutional Ethics Committee with Reference number IEC/29/20 dated July 20, 2020. Informed written consent was obtained from all patients. A total of 150 cases of acute leukemia were included in the study. The diagnosis was based on morphology, cytochemistry, and immunophenotyping by flowcytometry as B-ALL (n = 76), T-ALL (n = 8), AML (n = 65), and Mixed phenotype Acute Leukemia (MPAL, n = 1).
Sample collection and processing
Three mililiters of peripheral blood/bone marrow aspirate sample was collected in Ethylenediamine tetra-acetate vials. Complete blood counts were done on Sysmex XN-1000 and smears were examined using Giemsa and special stains-Myeloperoxidase, Periodic Acid Schiff and Nonspecific esterase stain.
Flowcytometric immunophenotyping was done within 24 h of collection using the standard stain-lyse-wash procedure using a panel of monoclonal antibodies labeled with various fluorochromes-V450, V500c, Fluorescein isothiocyanate, Phycoerythrin (PE), Peridinin chlorophyll protein-Cy5.5 (PerCPCy5.5), PECy7, Allophycocyanin (APC) and APC-H7 [Table 1].
The sample was acquired (minimum 50,000 events) in BD FACS Canto II eight color flowcytometer and analyzed using FACS DIVA software. Blasts were gated using Side scatter (SSC) versus Forward scatter (FSC) followed by SSC versus CD45 plot. Doublets were excluded based on FSC-area versus FSC-height plots. Negative controls were run simultaneously in every case. The expression of various surface and cytoplasmic markers was analyzed on the target population. The cut-offs of surface and cytoplasmic markers were taken as ≥20% and ≥10% respectively.
Based on the positivity of aberrant lymphoid/myeloid antigens (Ly+/My+), AML cases were stratified into Ly + AML and Ly− AML while ALL cases were subdivided into My + ALL and My− ALL. These groups were compared with respect to mean hemoglobin, mean total leukocyte count (TLC), mean platelet count, and percentage of blasts in peripheral blood using Independent t-test. Significance was assessed at P ≤ 0.05.
| Results|| |
The age of patients (n = 150) ranged from 4 years to 69 years with a mean age of 27.5 years. There were 79 males and 71 females with a male:female ratio of 1.1. The distribution of cases was as follows: 76 B-ALL, 8 T-ALL, 65 AML, and one MPAL.
Out of the 150 cases, 65 (43.3%) had conventional immunophenotypes as they showed expression of lineage-specific markers, whereas 85 (56.7%) demonstrated the expression of aberrant markers. The lineage specific markers are depicted in [Table 2].
The proportional frequency of conventional and aberrant cases is summarized in [Table 3].
|Table 3: Proportional frequency of cases with conventional and aberrant phenotype|
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Out of the 43 cases of B-ALL with aberrant myeloid antigen expression (My + B-ALL), 18 (41.9%) showed CD13 expression followed by 10 (23.3%) with CD33 and 8 (18.6%) with CD117 expression. Paired aberrant expression was seen in 10 cases of B-ALL with CD13/CD33 being the most common pair followed by CD13/CD117.
Out of the four cases of T-ALL with aberrant myeloid antigen expression (My + T-ALL), three (75%) depicted CD13 aberrancy followed by two (50%) with CD33 expression. CD13/CD33 was the most frequent aberrant pair seen among the cases of T-ALL.
Among the 38 cases of AML with aberrant lymphoid expression (Ly + AML), 22 (57.9%) demonstrated CD7 aberrancy followed by six cases (15.8%) each with CD2 and CD5 aberrancy.
The aberrant expression of CD markers in acute leukemia is depicted in [Table 4].
|Table 4: Aberrant expression of cluster of differentiation markers in acute leukemia|
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The mean white cell count and percentage of blasts in peripheral blood was significantly lower in My + B-ALL as compared to My− B-ALL. On the contrary, both these parameters were significantly raised in Ly + AML as compared to Ly− AML. No such correlation could be derived between My + T-ALL/My− T-ALL groups with respect to the hematological parameters [Table 5].
|Table 5: Comparison of hematological parameters between the cases with conventional and aberrant phenotype|
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| Discussion|| |
The present study analyzed immunophenotype of blasts from 150 cases of acute leukemia to determine the frequency of aberrant markers. Out of the 150 cases, 85 (56.7%) demonstrated expression of aberrant markers. These results are similar to the findings of Sarma et al. and Lopes et al.,
The proportional frequency of aberrancy in AML, B-ALL, and T-All was 58.5%, 56.6%, and 50%, respectively, which was in concordance with results of Sarma et al. [Table 6].
|Table 6: Comparison of proportional frequency of aberrant cases in different studies|
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Other studies had varied results with respect to the frequency of aberrancy in different types of acute leukemia [Table 7].,,,,,,,,,
|Table 7: Comparison of most common aberrant marker in acute leukemia in different studies|
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The most common aberrant markers in AML, B-ALL, and T-All observed in the present study were CD7, CD13, and CD13, respectively. The most common aberrancy in B-ALL was CD13 in majority studies,,,,,,,,, except Bhushan et al., Momani et al., and Sivakumar et al. who concluded CD33 as the most common aberrant marker in B-ALL.
Most studies observed CD13 as the most frequent aberrancy in T-ALL except Chaudhary et al., Bhushan et al., and Sharma et al. where CD33 was concluded as the most common aberrancy.,,
In AML, CD7 was demonstrated as the most prevalent aberrancy by majority studies except Bhushan et al., Aparna and Murugesan, and Gupta et al. where CD19 was observed as the most common aberrant marker [Table 7].,,
In the present study, My + B-ALL was associated with a lower mean TLC count and lesser number of blasts in peripheral blood as compared to My− B-ALL. This was in concordance with finding of Sharma et al. On the contrary, Lopes et al. demonstrated a higher platelet count in B-ALL with aberrant myeloid phenotype which was not observed in the current study. Sivakumar and Basu observed a higher TLC and platelet count in My + B-ALL. However, Bhushan et al. did not find any significant difference in hematological parameters between My + B-ALL and My− B-ALL.
We observed a higher TLC and increased percentage of blasts in peripheral blood in Ly + AML as compared to Ly− AML. This is in concordance with the findings of Sharma et al. On the contrary, Bhushan et al. and Aparna and Murugesan found no significant association between hematological parameters and aberrant lymphoid phenotype in AML.,
| Conclusion|| |
Multiparameter flowcytometry is a useful method for the identification of leukemic cells and for detection of expression of aberrant markers. My + B-ALL is associated with a lower TLC and peripheral blood blast percentage and thus is not associated with adverse hematological features. However, Ly + AML is associated with a higher TLC and peripheral blood blast percentage portending an unfavorable outcome. The identification of these aberrant phenotypes helps in monitoring MRD and deciding alternate treatment options. More studies with greater follow-up period are required to establish prognostic significance of aberrant markers in acute leukemia.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]