EFB Dengue Literature Review

CD23

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CD23

Overview

CD23 (FcεRII, low-affinity IgE receptor) is expressed on resting naive and transitional B cells and is downregulated upon sustained B cell activation. In flow cytometry, CD23 expression status (CD23⁺ vs. CD23⁻) within the IgD⁺CD27⁻ naive compartment can help discriminate resting naive cells from recently activated naive cells. CD23 downregulation is induced by sustained BCR signalling, TLR9 activation, IFN-α, and IFN-γ — all pathways active in SLE and in acute viral infections.

Key Points from Literature

  • CD23⁻ phenotype marks acN cells in SLE: Activated naive (acN) B cells (CD19^hi, IgD⁺, CD27⁻, MTG⁺, CD24⁻, CD21⁻) are CD23⁻, consistent with downregulation by sustained activation pathways. Longitudinal tracking of CD23⁻ cells within the IgD⁺CD27⁻ naive compartment of SLE patients showed correlation with disease activity across moderate and severe flares (see Tipton2015 - ASC Diversity and Origin in SLE, 13 longitudinal experiments across 3 patients).
  • CD23 downregulation by activation stimuli: CD23 expression is reduced by sustained BCR activation, TLR9 stimulation, IFN-α, and IFN-γ — signalling pathways prominent in SLE. This mechanistic basis suggests CD23⁻ cells within the naive compartment are not a fixed developmental subset but reflect ongoing activation state (see Tipton2015 - ASC Diversity and Origin in SLE, citing Hanten et al. 2008 and Delespesse et al. 1989).
  • Potential utility as a disease-activity marker: CD23 negativity within the IgD⁺CD27⁻ gate was used as a surrogate for acN cell frequency in longitudinal analyses, as it requires fewer reagents than the full MTG + CD24 panel. Changes in CD23⁻ frequency tracked with flare severity (see Tipton2015 - ASC Diversity and Origin in SLE).

Contradictions & Debates

  • CD23 downregulation can occur by multiple mechanisms (shedding, transcriptional repression) and is not restricted to acN cells — it may also mark other activated B cell subsets. Its specificity as a surrogate for acN cells has not been formally validated against the full MTG/CD24 gating scheme.

Activated Naive B Cell, CD21, CD24, Extrafollicular Response, Conventional Flow Cytometry

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