Light-inducible T cell engagers trigger, tune and shape the activation of primary T cells

To mount appropriate responses, T cells integrate complex sequences of receptor stimuli perceived during transient interactions with antigen presenting cells. Although it has been hypothesized that the dynamics of these interactions influence the outcome of T cell activation, methodological limitations have hindered its formal demonstration. Here, we have engineered the Light-inducible T cell engager (LiTe) system, a recombinant optogenetics-based molecular tool targeting the T Cell Receptor (TCR). The LiTe system constitutes a reversible molecular switch displaying exquisite reactivity. As proof of concept, we dissect how specific temporal patterns of TCR stimulation shape T cell activation patterns. We established that CD4+ T cells respond to intermittent TCR stimulation more efficiently than their CD8+ T cells counterparts and provide evidence that distinct sequences of TCR stimulation encode different cytokine programs. Finally, we show that the LiTe system could be exploited to create light-activated bispecific T cell engagers and manipulate tumor cell killing. Overall, the LiTe system provides new opportunities to understand how T cells integrate TCR stimulations and to trigger T cell cytotoxicity with a high spatiotemporal control.