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Polyclonal CD5+/CD19+ B1a lymphocytes after allogeneic stem cell transplantation: a potential diagnostic pitfall

Amir Qorbani; Guofeng Gao; Denis M. Dwyre

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In adults, B-lymphocytes comprise approximately 10% of circulating lymphocytes. The majority of peripheral B cells are B2 cells (“Mature” B-cells), which function as part of the humoral adaptive immune system. B1 cells (“Innate-like” B cells) are another sub-class of B lymphocytes, considered as innate immune cells with a characteristic phenotype (CD20+, CD27+, CD43+, CD70-, CD11b+, sIgM++, sIgD+) which can be divided into two subtypes; B1a (CD5+): spontaneously produce broadly reactive natural IgM, and B1b (CD5-): can generate T-cell independent, long-lasting IgM. There is very limited data available, indicating a correlation between allogeneic bone marrow transplantation and an increase in B1a cells. Here we present a case of a 17-year-old female with homozygous sickle cell disease (HbSS disease) who underwent hematopoietic stem cell transplant (HSCT). Approximately seven months post-transplant, she was found to have 16% immature mononuclear cells on complete blood count (CBC)-differential report. A follow-up peripheral blood flow cytometry showed that these cells were polyclonal CD5+/CD20+ B-cells, and comprised 66% of lymphocytes. Further workup and follow up failed to reveal any lymphoproliferative disorders. It is important not to misdiagnose these cells as an atypical CD5+ lymphoproliferative disorder. The presence of B1a cells has not been widely reported in non-neoplastic post-stem cell transplanted patients. This case also adds to and expands our knowledge regarding the presence of increased circulating B1a cells after stem cell transplant in a patient with no history of hematological malignancy.


Flow Cytometry, Hematology, Pathology, Stem Cell Transplantation


Kantor A. A new nomenclature for B cells.

Immunol Today. 1991;12(11):388. []. [PMID:1786071]

Caligaris-Cappio F, Ferrarini M. B cells and their fate in health and disease.

Immunol Today. 1996;17(5):206-8. []. [PMID:8991379]

Hayakawa K, Hardy RR, Herzenberg LA, Herzenberg LA. Progenitors for Ly-1 B cells are distinct from progenitors for other B cells.

J Exp Med. 1985;161(6):1554-68. []. [PMID:3874257]

Baumgarth N. The double life of a B-1 cell: self-reactivity selects for protective effector functions.

Nat Rev Immunol. 2011;11(1):34-46. []. [PMID:21151033]

Griffin DO, Rothstein TL. Human b1 cell frequency: isolation and analysis of human b1 cells.

Front Immunol. 2012;3:122. []. [PMID:22654880]

Lydyard PM, Quartey-Papafio R, Bröker B, et al. The antibody repertoire of early human B cells. I. High frequency of autoreactivity and polyreactivity.

Scand J Immunol. 1990;31(1):33-43. []. [PMID:2154032]

Hannet I, Erkeller-Yuksel F, Lydyard P, Deneys V, DeBruyère M. Developmental and maturational changes in human blood lymphocyte subpopulations.

Immunol Today. 1992;13(6):215-218. [].

Krop I, de Fougerolles AR, Hardy RR, Allison M, Schlissel MS, Fearon DT. Self-renewal of B-1 lymphocytes is dependent on CD19.

Eur J Immunol. 1996;26(1):238-42. []. [PMID:8566073]

Ansel KM, Harris RBS, Cyster JG. CXCL13 is required for B1 cell homing, natural antibody production, and body cavity immunity.

Immunity. 2002;16(1):67-76. []. [PMID:11825566]

Chen Y, Park YB, Patel E, Silverman GJ. IgM antibodies to apoptosis-associated determinants recruit C1q and enhance dendritic cell phagocytosis of apoptotic cells.

J Immunol. 2009;182(10):6031-43. []. [PMID:19414754]

Kaminski DA, Stavnezer J. Enhanced IgA class switching in marginal zone and B1 B cells relative to follicular/B2 B cells.

J Immunol. 2006;177(9):6025-9. []. [PMID:17056527]

Rothstein TL, Griffin DO, Holodick NE, Quach TD, Kaku H. Human B-1 cells take the stage.

Ann N Y Acad Sci. 2013;1285(1):97-114. []. [PMID:23692567]

Daniel O, Griffin DO, Holodick NE, Rothstein TL. Human B1 cells in umbilical cord and adult peripheral blood express the novel phenotype CD20+CD27+CD43+CD70−.

J Exp Med. 2011;208(1):67-80. []. [PMID:21220451]

Alugupalli KR, Leong JM, Woodland RT, Muramatsu M, Honjo T, Gerstein RM. B1b lymphocytes confer T cell-independent long-lasting immunity.

Immunity. 2004;21(3):379-90. []. [PMID:15357949]

Youinou P, Jamin C, Lydyard PM. CD5 expression in human B-cell populations.

Immunol Today. 1999;20(7):312-6. []. [PMID:10379049]

Dono M, Burgio VL, Tacchetti C, et al. Subepithelial B cells in the human palatine tonsil. I. Morphologic, cytochemical and phenotypic characterization.

Eur J Immunol. 1996;26(9):2035-42. []. [PMID:8814243]

Youinou P, Lydyard PM. CD5+ B cells in nonorgan-specific autoimmune diseases: a fresh look.

Lupus. 2001;10(8):523-5. []. [PMID:11530992]

Zuckerman E, Slobodin G, Kessel A, et al. Peripheral B-cell CD5 expansion and CD81 overexpression and their association with disease severity and autoimmune markers in chronic hepatitis C virus infection.

Clin Exp Immunol. 2002;128(2):353-8. []. [PMID:11985527]

Fuda FS, Karandikar NJ, Chen W. Significant CD5 expression on normal stage 3 hematogones and mature B Lymphocytes in bone marrow.

Am J Clin Pathol. 2009;132(5):733-7. []. [PMID:19846815]

Moins-Teisserenc H, Busson M, Herda A, et al. CD19+CD5+ B cells and B1-like cells following allogeneic hematopoietic stem cell transplantation.

Biol Blood Marrow Transplant. 2013;19(6):988-91. []. [PMID:23507469]

Antin JH, Ault KA, Rappeport JM, Smith BR. B lymphocyte reconstitution after human bone marrow transplantation: leu-1 antigen defines a distinct population of B lymphocytes.

J Clin Invest. 1987;80(2):325-32. []. [PMID:3112184]

Veneri D, Franchini M, de Sabata D, et al. Peripheral blood CD5-positive B lymphocytes (B1a cells) after allogeneic stem cell transplantation for acute myeloid leukaemia in humans.

Blood Transfus. 2008;6(4):220-4. [PMID:19112737]

Robert A, Hillard RA, Lekakis LJ, Pulliam JF. Increased polyclonal CD5+ B1a lymphocytes in a haploidentical stem cell transplant recipient.

Cytometry B Clin Cytom. 2011;80(2):119-21. [PMID:20890952]

Marti GE, Rawstron AC, Ghia P, et al. Diagnostic criteria for monoclonal B-cell lymphocytosis.

Br J Haematol. 2005;130(3):325-32. []. [PMID:16042682]

Ghosn EE, Yamamoto R, Hamanaka S, et al. Distinct B-cell lineage commitment distinguishes adult bone marrow hematopoietic stem cells.

Proc Natl Acad Sci USA. 2012;109(14):5394-8. []. [PMID:22431624]
































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