Mast cells promote malaria infection?

Abstract

PurposeMalaria remains the most deadly human parasitic disease, mostly because of the mosquito-born protozoan parasite Plasmodium falciparum with ~627,000 deaths reported in 2012. Unfortunately, there is resistance to most drugs, and successful vaccines are still not developed. The role of the immune system is critical but poorly understood. MethodsOne specific publication that reported a new way through which the immune system may promote malaria pathogenesis is discussed. FindingsKenyan children with mild and severe malaria had increased plasma levels of the Flt3 ligand, a soluble cytokine released from the surface of mast cells (MCs). A positive correlation was found between disease severity and frequencies of circulating BDCA3+ dendritic cells. These human equivalents of the rodent CD8+ T cells migrate to tissues with a heavy parasite load and cause damage primarily through cytolysis. ImplicationsMalaria parasites may promote malaria pathogenesis by triggering MCs, which expand a unique class of dendritic cells with the subsequent activation of pathogenic CD8+ T cells. However, MCs may have additional regulatory functions. Selective inhibition of MC activation may serve as an adjuvant treatment.