Malaria is a major public health concern, presenting more than 200 million cases per year worldwide. Despite years of scientific efforts, protective immunity to
malaria is still poorly understood, mainly due to methodological limitations of long-term Plasmodium culture, especially for Plasmodium vivax. Most studies have focused on adaptive immunity protection against
malaria by
antibodies, which play a key role in controlling
malaria. However, the sterile protection induced by attenuated Plasmodium sporozoites
vaccines is related to cellular response, mainly to cytotoxic T lymphocytes, such as CD8+ and gamma delta T cells (γδ T). Hence, new methodologies must be developed to better comprehend the functions of the cellular immune response and thus support future
therapy and
vaccine development. To find a new strategy to analyze this cell-mediated immunity to Plasmodium blood-stage
infection, our group established an in vitro assay that measures infected red blood cell (iRBC) killing by cytotoxic lymphocytes. This assay can be used to study cellular immune response mechanisms against different Plasmodium spp. in the blood stage. Innate and adaptative cytotoxic immune cells can directly eliminate iRBCs and the intracellular parasite in an effector:target mechanism. Target iRBCs are labeled to evaluate cell viability, and cocultured with effector cells (CD8+ T, γδ T, NK cells, etc.). The lysis percentage is calculated based on tested conditions, compared to a spontaneous lysis control in a flow cytometry-based assay. Ultimately, this killing assay methodology is a major advance in understanding cell-mediated immunity to blood-stage
malaria, helping uncover new potential therapeutic targets and accelerate the development of
malaria vaccines.