BAFF

Overview

BAFF (BLyS, TNFSF13B) is the B cell survival factor, acting through three receptors — BAFF-R, TACI and BCMA — of which TACI and BCMA are shared with the related ligand APRIL. This page covers BAFF and, because the wiki has too little on each individually, the receptor family as a whole.

BAFF is the axis on which this wiki holds its sharpest unresolved conflict: a murine review says atypical B cells are BAFF-independent, a dengue primary found no serum correlation with plasmablast output, and a second dengue primary found that blocking BAFF functionally reduces plasmablast differentiation. See Contradictions.

Background context (not sourced to an ingested paper): BAFF is produced largely by myeloid cells and stromal cells; belimumab is an anti-BAFF monoclonal approved in SLE.

Key Points from Literature

The dengue evidence — functional, and positive

• Genes encoding BAFF and APRIL were increased in the blood of dengue patients with high viraemia at the early stage of illness, and their expression correlated with the magnitude of the CD14⁺CD16⁺ monocyte population (see Kwissa2014 - Monocytes Drive Plasmablast Differentiation in Dengue, n=28 acute secondary dengue)
• APRIL protein trended higher in high-viral-load plasma, and DENV-infected monocytes secreted both BAFF and APRIL in vitro (see Kwissa2014 - Monocytes Drive Plasmablast Differentiation in Dengue)
• ★ Blockade: anti-BAFF and TACI-Fc each modestly diminished B cell proliferation and plasmablast differentiation, and TACI-Fc significantly reduced IgM production (see Kwissa2014 - Monocytes Drive Plasmablast Differentiation in Dengue, human in vitro, 4 donors). Blocking IL-6 or IP-10 did not reproduce the effect; anti-IL-10 did.
• The authors’ conclusion is that DENV-infected monocytes drive plasmablast differentiation via BAFF/APRIL and IL-10

The in vitro reconstruction — contributory, not obligate

• BAFF was one of six components in the defined cocktail (anti-Ig, IFN-γ, IL-2, IL-21, BAFF, R848) that drives naive B cells to the DN2 phenotype. Omitting BAFF had little effect on T-bet⁺IRF4⁺ pre-ASC induction (8.31% vs 8.32% for the full cocktail), and while its removal decreased the number of ASCs recovered, BAFF was explicitly not obligate for ASC development (see Zumaquero2019 - IFN-gamma Programs T-bet-hi B Cells for ASC Differentiation, human in vitro, ≥3 experiments)

The murine/ABC picture — competitive independence

• ABCs express BAFF-R and TACI and can consume or sequester BAFF, yet are themselves largely BAFF-independent, which is proposed to make them “exceptional competitors in BAFF-regulated homeostatic space” — i.e. they displace follicular B cells that do depend on BAFF (see Cancro2020 - Age-Associated B Cells, review, murine, zero original data — sole source for this mechanism)
• BCMA (Tnfrsf17) was among the genes most highly expressed in murine T-bet⁺CD11c⁺ B cells, alongside Prdm1, Xbp1, Zeb2 and Sdc1 — an ASC-associated receptor signature (see Song2022 - Tfh Outside Germinal Centers Drive T-bet CD11c B Cells, murine RNA-seq). BCMA has no separate page; this is currently its only wiki evidence.
• BAFF-R is lowest on DN3 cells among the DN subsets, together with CD22, CD72 and CD69 (see Lamprinou2026 - ABCs and DN B Cells, review). See DN3 B Cell.
• BAFF is essential for early memory B cell maintenance (see Glaros2025 - Multilayered Identity of B Cell Memory, review)
• BLyS/APRIL support CD40-independent class switch recombination (see Wei2007 - DN Memory B Cells in SLE, citing Litinskiy 2002 — not ingested). See Class Switch Recombination.
• Belimumab (anti-BAFF) is used therapeutically in SLE and is noted as the only new SLE drug in decades (see Lamprinou2026 - ABCs and DN B Cells and Zumaquero2019 - IFN-gamma Programs T-bet-hi B Cells for ASC Differentiation introduction, both review-carried)

Contradictions & Debates

★ The three-way BAFF tension (opened 2026-08-18)

Source	Type	Finding
Cancro2020 - Age-Associated B Cells	Review, murine, zero original data	ABCs express BAFF-R/TACI but are largely BAFF-independent
GarciaBates2013 - Plasmablast Response and Dengue Severity	Dengue primary	Serum BAFF/APRIL/IL-6/IL-10/IL-21 showed no correlation with plasmablast magnitude
Kwissa2014 - Monocytes Drive Plasmablast Differentiation in Dengue	Dengue primary	BAFF/APRIL transcripts correlated with monocyte expansion; blocking BAFF/APRIL reduced plasmablast differentiation (“modestly”)
Zumaquero2019 - IFN-gamma Programs T-bet-hi B Cells for ASC Differentiation	Human in vitro	Removing BAFF decreased ASC numbers but was not obligate

These are not flatly incompatible. A synthesis that fits all four is that BAFF/APRIL are contributory but not obligate — real enough that blockade reduces output, weak enough that removing it does not abolish differentiation, and delivered locally enough that serum concentration is uninformative.

Note that GarciaBates measured serum protein against in vivo plasmablast frequency, while Kwissa measured blood transcript plus in vitro blockade. These are different measurements of different things, and the discrepancy may be entirely methodological. The same serum-versus-local-delivery problem appears for IL-21 (see IL-21R Contradictions), where plasma IL-21 does not correlate with DN2 frequency despite IL-21R blockade removing 60% of the dengue plasmablast response.

Recorded as open per Rule 4. Do not write “BAFF drives the dengue plasmablast response” or “BAFF is irrelevant in dengue” — both overstate.

Related Pages

APRIL, TACI, Plasmablast, Inflammatory Monocyte, Age-Associated B Cell, DN3 B Cell, Class Switch Recombination, Atypical B Cell Effector Output, IL-21R, Extrafollicular Response

Sources

• Kwissa2014 - Monocytes Drive Plasmablast Differentiation in Dengue
• Zumaquero2019 - IFN-gamma Programs T-bet-hi B Cells for ASC Differentiation
• Cancro2020 - Age-Associated B Cells
• GarciaBates2013 - Plasmablast Response and Dengue Severity
• Song2022 - Tfh Outside Germinal Centers Drive T-bet CD11c B Cells
• Lamprinou2026 - ABCs and DN B Cells
• Wei2007 - DN Memory B Cells in SLE
• Glaros2025 - Multilayered Identity of B Cell Memory