EFB Dengue Literature Review

CD19

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CD19

Overview

CD19 is a type I transmembrane glycoprotein and co-receptor of the B cell receptor complex, expressed broadly on all B lineage cells from pro-B through mature B cells and lost upon terminal differentiation to plasma cells. It is the standard pan-B cell gate in flow cytometry panels; B cell subsets are conventionally defined as percentages of CD19⁺ cells.

Key Points from Literature

  • All B cell subset analyses in Wei et al. are gated on live CD19⁺ lymphocytes; percentages of naive, memory, DN, and plasma cells are reported as fractions of CD19⁺ PBL (see Wei2007 - DN Memory B Cells in SLE).

  • CD19 expression is used together with CD20 for FACS sorting of B cells for BCR sequencing: CD19⁺CD20⁺IgG⁺IgD⁻ cells were sorted into CD27⁺ and CD27⁻ fractions (see Wei2007 - DN Memory B Cells in SLE).

  • CD19^low as a plasmablast identifier: Plasmablasts downregulate CD19 upon terminal differentiation. In the combined gate CD38^high, CD19^low, CD20⁻, the CD19^low criterion helps exclude pre-GC cells (which remain CD19^bright). CD19 downregulation tracks with CD20 loss as B cells differentiate into antibody-secreting cells (see Anolik2004 - Rituximab and B Cell Abnormalities in SLE).

  • CD19^hi marks activated naive (acN) B cells: In contrast to the downregulation seen at the plasmablast stage, B cell activation upregulates CD19 surface expression. Within the IgD⁺CD27⁻ naive compartment, the CD19^hi fraction is dramatically enriched for activated (MTG⁺CD24⁻) acN cells in SLE flares, and these CD19^hi cells are selectively enriched for autoreactive 9G4⁺ B cells relative to the CD19⁺ resting fraction. CD19^hi expression tracks with CD21 downregulation upon activation (see Tipton2015 - ASC Diversity and Origin in SLE, citing Masilamani et al. 2003 and Wehr et al. 2004).

  • CD19^hi is a defining DN2 marker: DN2 B cells (IgD⁻CD27⁻CXCR5⁻CD21⁻CD11c⁺) express CD19 at a characteristically high level — the same CD19^hi expression shared with aNAV cells. CD19^hi is one of the markers that distinguishes DN2 from DN1 (CD19 intermediate). In the EF differentiation pathway (rNAV → aNAV → DN2), CD19^hi expression is acquired at the aNAV stage and retained through DN2. RNA-seq confirms that CD19 upregulation in DN2/aNAV is part of the broader activation programme (see Jenks2018 - DN2 B Cells and EF Pathway in SLE, flow cytometry + RNA-seq).

  • CD19⁺ as primary B cell gate in dengue plasmablast studies: In Wrammert2012, plasmablasts are gated as CD19⁺CD3⁻CD20⁻/low CD27^high CD38^high on an extended lymphocyte gate (to capture blasting cells). CD19⁺ is the anchor gate; plasmablast frequencies reported as percentage of CD19⁺ B cells (average 47% in acute dengue). This is the simplest dengue plasmablast panel in the wiki (5-color) and confirms CD19 as the universal B cell denominator across all dengue panels (see Wrammert2012 - Plasmablast Responses in Acute Dengue, 5-color conventional FCM).

  • CD19⁺ gate for both PB and MBC sorting in dengue clonal analysis: Appanna2016 used CD19⁺ as the anchor for both plasmablast sorting (CD19⁺CD20⁻CD27^hiCD38^hi) and DENV-specific MBC sorting (CD19⁺CD20⁺CD27⁺), confirming CD19 as the universal B cell gate across all dengue B cell studies. 0.1–19% of total lymphocytes were CD19⁺ plasmablasts; 0.5–8.1% of CD19⁺CD20⁺ B cells bound DENV (see Appanna2016 - Plasmablasts as Subset of Memory B Cell Pool, FACSAria, n=12 dengue).

Contradictions & Debates

None documented in current wiki sources.

CD20, CD38, Activated Naive B Cell, DN2 B Cell, Conventional Flow Cytometry, Double-Negative B Cell, Memory B Cell, Plasmablast

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