A secret reservoir of immune cells lives permanently inside the brain and only wakes up after a stroke.
April 26, 2026
Original Paper
Age-associated B cells (ABCs) develop from a CNS-localized progenitor pool into a pro-inflammatory phenotype after stroke
bioRxiv · 10.64898/2026.03.02.709112
The Takeaway
The brain's immune response was thought to rely on cells that travel from the blood or the spleen during an emergency. This research identifies a pool of B cell progenitors that are already residents of the central nervous system. In aging brains, these cells transform into highly inflammatory agents immediately after a stroke. This resident population contributes to brain damage much faster than cells arriving from elsewhere in the body. Targeting these local cells could be the key to reducing the long-term inflammation that follows a stroke.
From the abstract
Aging and age-related diseases like ischemic stroke induce chronic lymphocyte recruitment into the central nervous system (CNS). Conflicting effects on post-stroke functional recovery, however, are secondary to the differences in responding lymphocyte populations that shift immunophenotype with both ischemic injury and age. To better define CNS-localized B cell subsets, we used flow cytometry, single-cell RNA sequencing, and B cell receptor sequencing on B cells isolated from uninjured and post-