IMMUNOLOGY2026™ Conference Recordings For Attendees-A sinus-proximal fibroblast niche supports B lymphopoiesis in the developing dura mater

A sinus-proximal fibroblast niche supports B lymphopoiesis in the developing dura mater

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Video Summary

This session focused on early-life hematopoiesis, especially B cell development outside the bone marrow. Alec Walker presented evidence that the mouse dura mater contains a striking, transient wave of B cells peaking around postnatal day 14, clustered near dural sinuses in a specialized “sinus proximal” niche. Single-cell RNA sequencing showed these cells span multiple B cell developmental stages and express recombination genes, indicating local B cell generation. Similar extramedullary B cell development also occurs in spleen and intestine. Fate-mapping suggested early-life B cells rapidly seed mature B cell pools, especially follicular and marginal zone compartments. Data also hinted that different tissues may shape B cell receptor repertoires differently. In the dura, FOXD1-expressing CXCL12-high fibroblasts form a unique stromal niche required for this process; deleting CXCL12 in these cells reduced brain-border B cell development. The talk concluded that extramedullary niches may support rapid early-life immunity and diversify the BCR repertoire.

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Date April 16, 2026 4:15 PM - 4:30 PM

Room 104AB

Session Bone Marrow Hematopoiesis

Speaker Alec Walker

Track Hematopoiesis and Immune System Development (HEM)

Year 2026

Keywords

early-life hematopoiesis

extramedullary B cell development

dura mater

CXCL12 stromal niche

B cell receptor repertoire

April 16, 2026 4:15 PM - 4:30 PM

104AB

Bone Marrow Hematopoiesis

Alec Walker

Hematopoiesis and Immune System Development (HEM)

2026