Follicular dendritic cells restrict interleukin-4 availability in germinal centers and foster memory B cell generation Granhical abstract Authors Lihui Duan, Dan Liu, Hsin Chen,..., Jinping An, Brian J. Laidlaw, Jason G. Cyster Correspondence jason.cystereucsf.edu In brief B cells within germinal centers (GCs) enter cycles of antibody affinity maturation or exit the GC as memory cells or plasma cells. Duan et al. examine the contribution of interleukin (IL)-4 on B cell fate decisions in the GC and reveal that IL4Ra + GC follicular dendritic cells limit bystander IL-4 activity, focusing IL-4 action on B cells undergoing selection.