EFB Dengue Literature Review

Inflammatory Monocyte

5 min read

Inflammatory Monocyte

Overview

The intermediate CD14⁺CD16⁺ monocyte is the wiki’s only non-lymphoid cell with its own page, and it earns one because it is the extrinsic driver of the dengue plasmablast response — the answer to what pushes B cells down the extrafollicular route in dengue, as opposed to what the B cells do once pushed.

It also sits at the junction with Antibody-Dependent Enhancement: monocytes are the DENV target cell, they are decorated with Fcγ receptors, and they expand precisely when antibody is being made.

Background context (not sourced to an ingested paper): human blood monocytes are conventionally divided into classical CD14⁺CD16⁻, intermediate CD14⁺CD16⁺, and non-classical CD14^dim^CD16⁺⁺ subsets.

Key Points from Literature

Expansion in dengue

They are made by the virus, and by TLR7/8

★ They drive plasmablast differentiation, via BAFF/APRIL and IL-10

Independent replication of the severity association, in a second cohort

  • ★ Monocyte percentage is significantly higher in DHF than DF, and higher in both than in healthy controls. In an adult Mexican acute-phase cohort, monocytes were 14.44 ± 7.11% in DHF versus 10.33 ± 4.705% in DF (OR 2.095, 95% CI 1.075–4.083, p=0.0001), with the general population at 7.517 ± 2.646% (see Posadas-Mondragon2020 - TLR Polymorphisms and Clinical Forms of Dengue, n=254 case-control, DF n=100 / DHF n=65 / GP n=89, WHO 1997, DENV-2-dominant, days 1–8 post-onset). Lymphocyte percentage moved the same way (35.23 ± 14.88% vs 24.77 ± 14.38%, OR 3.467, p<0.0001) against a background of leukopenia and neutropenia. This is an independent geographic and demographic replication — adults in Veracruz, Mexico — of the monocyte expansion Kwissa2014 - Monocytes Drive Plasmablast Differentiation in Dengue reported in a Thai cohort and then tied causally to plasmablast differentiation.
  • ⚠ But it is a haematology-analyser measurement, not a subset measurement. The counts above come from a COULTER LH 500 and report total monocyte percentage only. Nothing in that study resolves CD14/CD16 subsets, so it cannot confirm that the expanded compartment is the CD14⁺CD16⁺ inflammatory subset that Kwissa2014 identified as the plasmablast-driving one — only that the parent population enlarges with severity (see Posadas-Mondragon2020 - TLR Polymorphisms and Clinical Forms of Dengue). Distinguishing the two is a cheap addition to any cohort already running a B cell panel.

Contradictions & Debates

A disagreement the source itself reports. Xu et al. 2012 (not ingested) found that CD163⁺ human macrophages stimulate CD138⁺⁺CD38⁺⁺ plasma cells through an IP-10- and IL-6-dependent mechanism. Kwissa2014 - Monocytes Drive Plasmablast Differentiation in Dengue explicitly did not observe IL-6- or IP-10-dependent plasmablast stimulation, attributing the effect instead to BAFF/APRIL and IL-10. Recorded as the ingested source’s own reported disagreement; the wiki cannot adjudicate without Xu 2012.

Does this pathway drive DN2 cells, or only plasmablasts? BAFF/APRIL/IL-10 is a different signal set from the IFN-γ/TLR7/IL-21 triad that generates DN2 cells (Jenks2018 - DN2 B Cells and EF Pathway in SLE, Zumaquero2019 - IFN-gamma Programs T-bet-hi B Cells for ASC Differentiation). Nothing in this wiki has run a monocyte–B cell coculture with a DN2 readout. Open, and directly testable.

Plasmablast, BAFF, APRIL, TACI, Type I Interferon, TLR7, CXCR3, Antibody-Dependent Enhancement, Extrafollicular Response, Atypical B Cell Effector Output, T-B Coculture Assay, Plasmacytoid Dendritic Cell

Sources

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