VLA-4
Overview
VLA-4 (α4β1, CD49d/CD29, encoded by Itga4 and Itgb1) is a β1 integrin whose ligand is VCAM-1. With LFA-1 it retains T-bet⁺CD11c⁺ B cells at the splenic marginal zone. The two are blocked together in the only experiment that demonstrates the mechanism, so their individual contributions are not separated — which is a reason to hold the two pages apart, not to merge them (merge considered and declined 2026-08-28 — see state.md Decisions).
Key Points from Literature
- T-bet⁺CD11c⁺ B cells showed elevated transcript and surface protein expression of VLA-4 compared with naive follicular B cells (see Song2022 - Tfh Outside Germinal Centers Drive T-bet CD11c B Cells, murine, day 15 post-LCMV)
- Itga4 and Itgb1 were upregulated in T-bet⁺CD11c⁺ cells relative to both GC and naive B cells (see Song2022 - Tfh Outside Germinal Centers Drive T-bet CD11c B Cells, murine RNA-seq, day 12)
- In vivo blockade of the LFA-1 and VLA-4 alpha subunits for 3 hours caused significant loss of these cells from spleen with a concomitant rise in blood (see Song2022 - Tfh Outside Germinal Centers Drive T-bet CD11c B Cells, murine, 3–4 mice/group)
- VLA-4 engages VCAM-1 at the marginal zone (see Song2022 - Tfh Outside Germinal Centers Drive T-bet CD11c B Cells, citing prior work)
- In a different compartment, α4β1 and α6β1 interactions with VCAM-1 are implicated in bone marrow memory B cell residency (see Glaros2025 - Multilayered Identity of B Cell Memory, review) — suggesting the same adhesion pair supports B cell residency at more than one site
Contradictions & Debates
None recorded — single-source murine finding, no counter-evidence, no human replication. See the scope caution on LFA-1.
Related Pages
LFA-1, S1PR3, CXCR3, Follicular Exclusion, Tissue-Resident Memory B Cell, Atypical B Cell Effector Output, DN2 B Cell