High-Throughput Functional Screening of Antigen-Specific T Cells Based on Droplet Microfluidics at a Single-Cell Level

The
lack of an efficient method for the identification of tumor
antigen-specific T cell receptors (TCRs) impedes the development of
T cell-based cancer immunotherapies. Here, we introduce a droplet-based
microfluidic platform for function-based screening and sorting of
tumor antigen-specific T cells with high throughput. We built a reporter
cell line by co-transducing the TCR library and reporter genes at
the downstream of TCR signaling, and reporter cells fluoresced upon
functionally binding with antigens. We co-encapsulated reporter cells
and antigen-presenting cells in droplets to allow for stimulation
on a single-cell level. Functioning reporter cells specific against
the antigen were identified in the microfluidic channel based on the
fluorescent signals of the droplets, which were immediately sorted
out using dielectrophoresis. We validated the reporter system and
sorting results using flow cytometry. We then performed single-cell
RNA sequencing on the sorted cells to further validate this platform
and demonstrate the compatibility with genetic characterizations.
Our platform provides a means for precise and efficient T cell immunotherapy,
and the droplet-based high-throughput TCR screening method could potentially
facilitate immunotherapeutic screening and promote T cell-based anti-tumor
therapies.