Previous malaria exposure attenuates monocyte-driven inflammation and shapes B cell immunity

Summary Clinical immunity to malaria develops after repeated malaria episodes. In this process, the inflammatory response is modulated to respond less vigorously upon reinfection. Monocytes are a major source of pro-inflammatory mediators during blood-stage infection and are known to adapt to repeated pathogen exposure. Here, we investigated the impact of previous malaria exposure on monocytes during blood-stage malaria by comparing the response in previously exposed and primary infected individuals. We observed reduced levels of the proinflammatory chemokine CXCL10 in previously exposed individuals, linked to changes in CD16 + monocytes. Similarly, BAFF levels were lower in these individuals and associated with modulation of monocyte and dendritic cells. This affected the BAFF-BAFF-R axis, crucial for B cell responses, translating to increasing parasite-specific antibody levels. Collectively, we present novel insights into how previous malaria exposure shapes monocyte responses during acute malaria and how these in turn impact the B cell compartment and humoral immune response.