Microfluidic-enabled production of DNA barcoded APC library (MEDAL) for high throughput T cell epitope screening

Screening for peptide fragments that can be displayed on antigen-presenting cells is an essential step in vaccine development. The current approach for this process is slow and costly as it involves separately pulsing cells with chemically synthesized peptides. We present Microfluidic-Enabled production of DNA-barcoded APC Library (MEDAL), a high throughput microfluidic droplet platform for parallel production of DNA-barcoded APCs loaded with enzymatically synthesized peptides. Droplets containing peptides and their encoding DNA are produced from microfluidic PCR-IVTT reaction. APCs presenting both peptides and DNA barcodes are obtained by injecting cells into these droplets. Up to 9,000 different APCs can be produced and screened within a 10-hour workflow. This approach allowed us to identify peptide sequences that bind to APCs expressing H-2Kb MHC class 1 molecule with next-generation sequencing of DNA barcodes.