EFB Dengue Literature Review

IgA

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IgA

Overview

IgA is the predominant immunoglobulin isotype at mucosal surfaces. In peripheral blood, IgA⁺ B cells represent a minor switched memory fraction. Like IgG, surface IgA expression marks cells that have undergone class switch recombination.

Key Points from Literature

  • DN (IgD⁻CD27⁻) B cells contain an IgA⁺ fraction in addition to IgG⁺ and IgM⁺ subsets — demonstrated in SLE patients (see Wei2007 - DN Memory B Cells in SLE, Fig. 8). The proportion of IgA⁺ cells within the DN compartment was not quantified numerically in the paper.

  • The presence of IgA⁺ cells in the DN compartment confirms that CD40-independent class switching (via BLyS/APRIL or other EF mechanisms) can produce IgA as well as IgG in extrafollicular settings (see Wei2007 - DN Memory B Cells in SLE).

  • IgA minor component of dengue plasmablast response: DENV-specific IgA-secreting plasmablasts were detectable in most patients but at ~100-fold lower frequency than IgG-secreting cells. This establishes IgA as a consistent but quantitatively minor isotype in the acute dengue plasmablast wave (see Wrammert2012 - Plasmablast Responses in Acute Dengue, ELISpot, n=46).

  • IgA sequences are present in circulating ASCs during SLE flares and vaccination responses, as part of the IgG + IgA switched isotype pool that constitutes the majority of ASC sequences in peripheral blood (see Tipton2015 - ASC Diversity and Origin in SLE, NGS isotype analysis).

  • IgA detected as a minor component in dengue PB and MBC BCR repertoires: In 454 sequencing of sorted plasmablast and MBC pools, IgA sequences were present alongside IgG and IgM. The isotype distribution showed IgG dominance in plasmablasts and non-DENV-binding MBCs, with IgM enrichment in DENV-binding MBCs. IgA contributed a minor fraction across all compartments (see Appanna2016 - Plasmablasts as Subset of Memory B Cell Pool, 454 sequencing, n=4 patients).

Contradictions & Debates

None documented in current wiki sources.

Double-Negative B Cell, IgG, IgM, Class Switch Recombination

Sources

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