Poster Presentation Second Round 16th Lorne Infection and Immunity 2026

Human Plasmodium falciparum sporozoite effector-memory CD8+ T cells exhibit epitope-specific activation and display distinct T cell receptor clustering   (#118)

Roos van Schuijlenburg 1 , Max van Houcke 2 , Jeroen Sijtsma 1 , Els Baalbergen 1 , Helena de Bes-Roeleveld 1 , Beatrice Winkel 1 , Krista E van Meijgaarden 1 , Sander Wuyts 2 , Blandine Franke-Fayard 1 , Meta Roestenberg 1
  1. Leiden University Center for Infectious Diseases (LUCID), Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, Leiden, Netherlands, Leiden, The Netherlands
  2. Immune Watch, Immune Watch, Antwerp, Belgium, Antwerp, Belgium

Malaria, caused by Plasmodium falciparum (Pf), remains a leading cause of morbidity and mortality globally. Despite strong evidence for a critical role for CD8+ T cells in protective immunity, and the importance of the liver-stage as a target, the specific mechanisms by which CD8+ T cells target particularly Plasmodium-infected liver cells remain unclear, particularly in humans. To address this, we investigated the activation and effector functions of human Pf sporozoite (SPZ)-specific memory CD8+ T cells. Using an in vitroantigen-presenting cell (APC) co-culture model, we demonstrated that repeated stimulation with Pf SPZ induced the differentiation of highly activated effector-memory (Tem) CD8+ T cells expressing CD137, IFN-γ, and perforin. T cell receptor (TCR) sequencing of the activated CD137+Pf SPZ memory T cell population revealed distinct TCR clusters, suggesting clonal expansion of several Pfepitope-specific T-cells. Additionally, when stimulated with several well-known liver-stage specific epitopes, including circumsporozoite protein (CSP), thrombospondin-related anonymous protein (TRAP), and liver-stage antigen-1 (LSA-1), only circumsporozoite protein-related antigen precursor (CRA) epitope GLLGNVSTV elicited significant activation of Pf SPZ memory CD8+ T cells. This epitope induces upregulation of key activation markers (CD137, IFN-γ) and cytotoxic molecules (perforin, Granzyme A and Granzyme B), evidencing strong recognition by Pf SPZ memory T cells. This study advances our understanding of human Pf SPZ memory CD8+ T cell responses and provides a novel approach for dissecting antigen specificity and memory development which would inform the design of more effective malaria vaccines.