Spatial confinement promotes germinal center diversity and tempers immunodominance.

Reduced germinal center confinement in mice leads to decreased overall B cell diversity and increased clonal skewing toward dominant clones.

• Why it matters: Understanding how spatial confinement influences germinal center B cell evolution is crucial because it affects antibody diversity and immune response quality, yet this role remains unclear.
• What they did: Using mice deficient in Gα13-dependent G-protein-coupled receptor signaling, researchers observed germinal center trafficking, performed multicolor clonal lineage tracing, and conducted spatial B cell receptor sequencing to compare confined and de-confined GCs.
• The result: De-confined GCs showed minimal diversification and greater clonal crossover, resulting in a less diverse B cell repertoire that favors clones targeting accessible epitopes, implying confinement supports antibody breadth.