The enigma of inverted lymph node architecture in pigs: insights into immune function and vaccination design.

It has been known for decades that pigs, as well as some other mammals, possess a peculiar lymph node architecture commonly referred to as "inverted". Although some direct consequences of this structure have been described, such as the altered circulation pattern of mature lymphocytes, the overall impact of this inversion on the induction and maturation of the adaptive immune response has never been explored. Here, we tentatively propose a series of hypotheses that could be experimentally tested. If confirmed, these hypotheses might prompt a reconsideration of conventional vaccination strategies in humans and perspectives for possibly improving the outcomes of vaccination in mammals possessing standard lymph nodes.