The microanatomic segregation of selection by apoptosis in the germinal center

B cells undergo rapid cell division and affinity maturation in anatomically distinct sites in lymphoid organs called germinal centers (GCs). Homeostasis is maintained in part by B cell apoptosis. However, the precise contribution of apoptosis to GC biology and selection is not well defined. We developed apoptosis-indicator mice and used them to visualize, purify, and characterize dying GC B cells. Apoptosis is prevalent in the GC, with up to half of all GC B cells dying every 6 hours. Moreover, programmed cell death is differentially regulated in the light zone and the dark zone: Light-zone B cells die by default if they are not positively selected, whereas dark-zone cells die when their antigen receptors are damaged by activation-induced cytidine deaminase.

Source: ScienceNOW - October 12, 2017 Category: Science Authors: Mayer, C. T., Gazumyan, A., Kara, E. E., Gitlin, A. D., Golijanin, J., Viant, C., Pai, J., Oliveira, T. Y., Wang, Q., Escolano, A., Medina-Ramirez, M., Sanders, R. W., Nussenzweig, M. C. Tags: Immunology, Online Only r-articles Source Type: news