Clonal selection

Schumacher and colleagues have designed a reporter system that allows in vivo tracking of replicative history over many cell generations. Using this system to study acute T cell responses, they uncover substantial diversity in past division of central memory CD8⁺ T cells and its link to cell state and recall potential.

The functional role of intestinal secretory IgA for host–microbiota interactions is investigated, showing that intestinal bacterial exposure leads to selection of diverse plasma cells that secrete antigen-specific IgA, which predominantly targets bacterial membranes.

Development of the T cells requires functions from thymic epithelial cells, whose development and function are epigenetically regulated. Here the authors show that inactivation of the polycomb repressive complex 2 (PRC2) alters the H3K27me3 configuration, reduces TEC functions, reveals a specific TEC subset, and hampers T cell development.

Xu and colleagues use single-cell transcriptomic analyses to uncover distinct expression dynamics of metabolic programs in germinal center B cells. Coupled analysis of transcriptional states and Igh variable sequences revealed that OXPHOS metabolism is enhanced in GC B cells undergoing positive selection. Their findings suggest BCR signaling tunes GC B cell metabolism to accelerate the cell cycle of positively selected GC B cells.

Antibody selection and maturation within B cells found in gut-associated germinal centres is stimulated by the gut microbiota, to a degree that depends on the presence and composition of the microbes.

T cell memory formation is often described as occurring during the chronic phases of infection. Buchholz and colleagues use the phenomenon of ‘memory inflation’ following cytomegalovirus infection to show that a tiny subset of self-renewing T cells branch off early from the bulk population to generate memory.