IL-2 Free Expansion of T Cells with Immunofilaments

Novel biomaterial-based cancer immunotherapeutic strategies, such as artificial antigen-presenting cells (aAPCs), focus on activating T cells through molecular cues presented on synthetic constructs aiming to improve T cell activation and direct differentiation. To meet these aims, aAPC designs that allow control over the ratio and density of the stimulatory signals are crucial. In this study, we used polyisocyanopeptide based immunofilaments (IF) as nanosized aAPCs to study the influence of ratio and density of αCD3 and αCD28 on T cell expansion and phenotype. We observed differences in T cell expansion, cytokine production, and effector phenotype, dependent on both the density and ratio. Interestingly, supplementation with 30 to 1000 U/mL IL-2 did not influence T cell expansion, cytokine production, or the effector phenotype of the optimal performing IFs. In contrast, IL-2 supplementation increased the number of terminal effector T cells, increased TIM3 expression, and significantly increased the levels of Tregs in the culture. Taken together, these results suggest that careful finetuning of the density and ratio of stimulatory antibodies on IFs can omit the need for IL-2 supplementation, which leads to a preferable phenotype. As such, our findings can be used to optimize T cell expansion protocols for ACT.