Trained immunity from the perspective of Plasmodium infection.

The immune system of vertebrates includes innate immunity and adaptive immunity, and the network between them enables the host to fight against invasions of various pathogens. Recently, studies discovered that immune memory is one of the features of innate immunity, breaking the previous opinion that immune memory exists only in adaptive immunity. Immune memory supports innate immune cells to respond efficiently upon reinfection or restimulation. During the Plasmodium infection, the innate immune system is the first to be triggered, and innate immune cells are activated by components from Plasmodium or Plasmodium-infected red blood cells. Innate immune cells could be induced to develop memory after the activation and may play an important role in the subsequent infection of Plasmodium or other pathogens and stimulation. This review will discuss the recent findings relevant to trained immunity and Plasmodium infection, facilitating the understanding of the role of trained immunity in malaria and other diseases and the development of therapeutic strategies based on trained immunity.