How can immune memory actually be getting stronger?
Research from immunologist Ali Ellebedy, at Washington University School of Medicine in St Louis, Missouri, helps to explain the vigour of the memory-B-cell response. His group took samples from the lymph nodes of
vaccinated individuals and found tiny B-cell finishing schools — called germinal centres — that
were churning out ever more potent immune cells as time went on6.
B cells in these structures randomly mutate their genes to create entire new sets of antibodies. Those cells that produce the best antibody repertoires eventually win out through an evolutionary process that augments the immune system’s ability to fight off Delta and other SARS-CoV-2 variants of concern.
Ellebedy and his colleagues initially described the persistence of these germinal centres for 15 weeks post-immunization
with an RNA-based jab —
longer than anyone had ever seen before with older-technology vaccines for other ailments. Now, the researchers have unpublished data, following the germinal centres for up to six months. “The training camp is still going,” Ellebedy says.
“It’s amazing.”