γδ T Cells Kill <i>Plasmodium falciparum</i> in a Granzyme- and Granulysin-Dependent Mechanism during the Late Blood Stage
María Andrea Hernández-Castañeda, Katharina Happ, Filippo Cattalani, Alexandra Wallimann, Marianne Blanchard, Isabelle Fellay, Brigitte Scolari, Nils Lannes, Smart Ikechukwu Mbagwu, Benoı̂t Fellay, Luis Filgueira, Pierre‐Yves Mantel, Michael Walch
Abstract
Abstract Plasmodium spp., the causative agent of malaria, have a complex life cycle. The exponential growth of the parasites during the blood stage is responsible for almost all malaria-associated morbidity and mortality. Therefore, tight immune control of the intraerythrocytic replication of the parasite is essential to prevent clinical malaria. Despite evidence that the particular lymphocyte subset of γδ T cells contributes to protective immunity during the blood stage in naive hosts, their precise inhibitory mechanisms remain unclear. Using human PBMCs, we confirmed in this study that γδ T cells specifically and massively expanded upon activation with Plasmodium falciparum culture supernatant. We also demonstrate that these activated cells gain cytolytic potential by upregulating cytotoxic effector proteins and IFN-γ. The killer cells bound to infected RBCs and killed intracellular P. falciparum via the transfer of the granzymes, which was mediated by granulysin in a stage-specific manner. Several vital plasmodial proteins were efficiently destroyed by granzyme B, suggesting proteolytic degradation of these proteins as essential in the lymphocyte-mediated death pathway. Overall, these data establish a granzyme- and granulysin-mediated innate immune mechanism exerted by γδ T cells to kill late-stage blood-residing P. falciparum.