Same arm, stronger immunity
Scientists from Sydney have discovered that administering a booster dose in the same arm as the initial vaccination can elicit a faster and more effective immune response. Published in Cell, their findings provide new insights that could inform future vaccination strategies.
The researchers found that after vaccination, macrophages in nearby lymph nodes undergo "priming," preparing them to guide memory B cells for a more rapid and robust response if the booster is delivered to the same site. Previous work showed that memory B cells - critical for mounting antibody responses upon reinfection -tend to reside in the lymph node closest to the original injection.
Using advanced imaging, the team observed that memory B cells migrate to the outer layer of the local lymph node, where they closely interact with resident macrophages. When a booster is given in the same arm, these primed macrophages efficiently capture the antigen and activate memory B cells to produce high-quality antibodies. The study underscores that beyond their established roles in pathogen clearance and dead cell removal, macrophages near the injection site also play a pivotal role in coordinating a potent secondary immune response.
