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MONOCLONAL B-CELL LYMPHOCYTOSIS IN THAI POPULATION: PREVALENCE AND IMMONOPHENOTYPIC CHARACTERISTICS
Author(s):
Piyanuch Kongtim
,
Piyanuch Kongtim
Affiliations:
Hematology,Faculty of Medicine Thammasat University,Pathumthani,Thailand
Jadsadagon Chantakarm
,
Jadsadagon Chantakarm
Affiliations:
Hematology,Faculty of Medicine Thammasat University,Pathumthani,Thailand
Wasithep Limvorapitak
,
Wasithep Limvorapitak
Affiliations:
Hematology,Faculty of Medicine Thammasat University,Pathumthani,Thailand
Naree Wanisorn
,
Naree Wanisorn
Affiliations:
Pathology,Faculty of Medicine Thammasat University,Pathumthani,Thailand
Thivaratana Sinthuwiwat
,
Thivaratana Sinthuwiwat
Affiliations:
Cancer Cytogenetic and Molecular Diagnostic,Chulabhorn Research Institute, Bangkok,Thailand
Wandee Udomchaiprasertkul
,
Wandee Udomchaiprasertkul
Affiliations:
Cancer Cytogenetic and Molecular Diagnostic,Chulabhorn Research Institute,Bangkok,Thailand
Surapol Issaragrisil
Surapol Issaragrisil
Affiliations:
Hematology,Faculty of Medicine Siriraj Hospital Mahidol University, Bangkok,Thailand
(Abstract release date: 05/18/17) EHA Library. Kongtim P. 05/18/17; 182492; PB1778
Piyanuch Kongtim
Piyanuch Kongtim
Contributions
PDF Abstract
Abstract

Abstract: PB1778

Type: Publication Only

Background

Monoclonal B-cell lymphocytosis (MBL) is characterized by the presence of <5X109 clonal B-cells/L in peripheral blood (PB) in otherwise healthy subjects, in the absence of symptoms and signs of a B-cell lymphoproliferative disorder (LPD). MBL is considered a precursor to chronic lymphocytic leukemia (CLL) and other B-cell malignancies.

Aims

To study the immunophenotypic features and prevalence of MBL in healthy Thai individuals.

Methods

Peripheral blood (PB) samples from 616 healthy Thai individuals (313 female), 18-80 year-old with normal lymphocyte counts were immunophenotyped using high-sensitive flow cytometry, based on 5-color staining and the screening for >5 × 106 total PB leukocytes. The initial PB samples were screened for clonal B cells using MultiMix Triple-Color Reagent (Kappa Light Chains/FITC, Lamba Light Chains/RPE and CD19/RPE-Cy5). In those cases in which a clonal B cell population was detected by imbalanced of sIgK:sIgL ratio of >3:1 or <1:3, were further tested for CD5, CD23, CD20 and CD79a expression.

Results
Of total 616 subjects, MBL was found in 8 cases (1.2%) including 3 and 5 female and male cases respectively. Among 40 years or older, MBL was found in 5 out of 448 cases (1.1%). Compared with non-MBL group, subjects in MBL group were significantly older (median age of 78 years versus 50 years; p=0.01) and had a significant higher number of absolute and B-lymphocyte count (median 3.1 versus 1.6 X 109/L; p=0.03 and 0.35 versus 0.16 X109/L; p=0.02, respectively) while the median white blood cell count was not different between 2 groups. Also, there were more subjects in MBL group who had family history of lymphoproliferative diseases (LPD; 37% vs 0%; p<0.01) and influenza vaccination within 2 years (50% vs. 8.7%; p=0.003).

Among 8 cases with MBL clone, 6 cases had low-count MBL (<0.5X109 clonal B-cells/L) while only 2 cases had high-count MBL (>0.5X109 clonal B-cells/L). All 8 cases had persistent positivity of MBL clone after tested was repeated within 3 months after the initial test. In the follow up test, only 1 case with initial high-count MBL had decrease number of B cell clone and became low count MBL.
There was not significant different in age between subjects in low and high-count MBL group. Six cases had typical CLL phenotype MBL clone (CD5+, CD23+, CD20+/dim and light chain restriction). Whereas 1 case had atypical CLL phenotype MBL (CD5+, CD20+ and light chain restriction but CD23-) and 1 case had non-CLL phenotype MBL (CD20+ but CD5-).
In univariate analysis, age (RR 4.19; 95%CI 1.0-17.7; p=0.049), absolute lymphocyte count (RR 2.76; 95%CI 1.01-4.87; p=0.047), family history of LPD (RR 122; 95%CI 51.1-293.4; p< 0.001) and influenza vaccination (RR 10.47; 95%CI 2.54-43.07; p=0.003) were associated with increase risk of developing MBL. After adjusted for age, only history of influenza vaccination and family history of LPD were an independent risk factor for developing MBL with age adjusted RR of 9.75 (95%CI 2.3-40.5; p=0.002) and 92 (95%CI 56.3-149.5; p<0.001), respectively.

Conclusion

MBL prevalence in Thai population is much lower than previously reported. It more frequent in elderlies and associated with family history of LPD and influenza vaccination. Although uncommon, the presence of high-count MBL warrants further investigations to define the biological and clinical significance in term of LPD transformation and long-term survival.

Session topic: 6. Chronic lymphocytic leukemia and related disorders - Clinical

Keyword(s): Lymphoproliferative disorder, Immunophenotype, Chronic Lymphocytic Leukemia

Abstract: PB1778

Type: Publication Only

Background

Monoclonal B-cell lymphocytosis (MBL) is characterized by the presence of <5X109 clonal B-cells/L in peripheral blood (PB) in otherwise healthy subjects, in the absence of symptoms and signs of a B-cell lymphoproliferative disorder (LPD). MBL is considered a precursor to chronic lymphocytic leukemia (CLL) and other B-cell malignancies.

Aims

To study the immunophenotypic features and prevalence of MBL in healthy Thai individuals.

Methods

Peripheral blood (PB) samples from 616 healthy Thai individuals (313 female), 18-80 year-old with normal lymphocyte counts were immunophenotyped using high-sensitive flow cytometry, based on 5-color staining and the screening for >5 × 106 total PB leukocytes. The initial PB samples were screened for clonal B cells using MultiMix Triple-Color Reagent (Kappa Light Chains/FITC, Lamba Light Chains/RPE and CD19/RPE-Cy5). In those cases in which a clonal B cell population was detected by imbalanced of sIgK:sIgL ratio of >3:1 or <1:3, were further tested for CD5, CD23, CD20 and CD79a expression.

Results
Of total 616 subjects, MBL was found in 8 cases (1.2%) including 3 and 5 female and male cases respectively. Among 40 years or older, MBL was found in 5 out of 448 cases (1.1%). Compared with non-MBL group, subjects in MBL group were significantly older (median age of 78 years versus 50 years; p=0.01) and had a significant higher number of absolute and B-lymphocyte count (median 3.1 versus 1.6 X 109/L; p=0.03 and 0.35 versus 0.16 X109/L; p=0.02, respectively) while the median white blood cell count was not different between 2 groups. Also, there were more subjects in MBL group who had family history of lymphoproliferative diseases (LPD; 37% vs 0%; p<0.01) and influenza vaccination within 2 years (50% vs. 8.7%; p=0.003).

Among 8 cases with MBL clone, 6 cases had low-count MBL (<0.5X109 clonal B-cells/L) while only 2 cases had high-count MBL (>0.5X109 clonal B-cells/L). All 8 cases had persistent positivity of MBL clone after tested was repeated within 3 months after the initial test. In the follow up test, only 1 case with initial high-count MBL had decrease number of B cell clone and became low count MBL.
There was not significant different in age between subjects in low and high-count MBL group. Six cases had typical CLL phenotype MBL clone (CD5+, CD23+, CD20+/dim and light chain restriction). Whereas 1 case had atypical CLL phenotype MBL (CD5+, CD20+ and light chain restriction but CD23-) and 1 case had non-CLL phenotype MBL (CD20+ but CD5-).
In univariate analysis, age (RR 4.19; 95%CI 1.0-17.7; p=0.049), absolute lymphocyte count (RR 2.76; 95%CI 1.01-4.87; p=0.047), family history of LPD (RR 122; 95%CI 51.1-293.4; p< 0.001) and influenza vaccination (RR 10.47; 95%CI 2.54-43.07; p=0.003) were associated with increase risk of developing MBL. After adjusted for age, only history of influenza vaccination and family history of LPD were an independent risk factor for developing MBL with age adjusted RR of 9.75 (95%CI 2.3-40.5; p=0.002) and 92 (95%CI 56.3-149.5; p<0.001), respectively.

Conclusion

MBL prevalence in Thai population is much lower than previously reported. It more frequent in elderlies and associated with family history of LPD and influenza vaccination. Although uncommon, the presence of high-count MBL warrants further investigations to define the biological and clinical significance in term of LPD transformation and long-term survival.

Session topic: 6. Chronic lymphocytic leukemia and related disorders - Clinical

Keyword(s): Lymphoproliferative disorder, Immunophenotype, Chronic Lymphocytic Leukemia

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