Activation and degranulation of CAR-T cells using engineered antigen-presenting cell surfaces

Adoptive cell transfer of Chimeric Antigen Receptor (CAR)-T cells showed promising results in patients with B cell malignancies. However, the detailed mechanism of CAR-T cell interaction with the target tumor cells is still not well understood. This work provides a systematic method for analyzing the activation and degranulation of second-generation CAR-T cells utilizing antigen-presenting cell surfaces. Antigen-presenting cell surfaces composed of circular micropatterns of CAR-specific anti-idiotype antibodies have been developed to mimic the interaction of CAR-T cells with target tumor cells using micro-contact printing. The levels of activation and degranulation of fixed non-transduced T cells (NT), CD19.CAR-T cells, and GD2.CAR-T cells on the antigen-presenting cell surfaces were quantified and compared by measuring the intensity of the CD3ζ chain phosphorylation and the Lysosome-Associated Membrane Protein 1 (LAMP-1), respectively. The size and morphology of the cells were also measured. The intracellular Ca2+ flux of NT and CAR-T cells upon engagement with the antigen-presenting cell surface was reported. Results suggest that NT and CD19.CAR-T cells have comparable activation levels, while NT have higher degranulation levels than CD19.CAR-T cells and GD2.CAR-T cells. The findings show that antigen-presenting cell surfaces allow a quantitative analysis of the molecules involved in synapse formation in different CAR-T cells in a systematic, reproducible manner.