Protocol for high-throughput compound screening using flow cytometry in THP-1 cells

Flow cytometry is a valuable method for analyzing protein expressions at the single cell level but can be difficult to apply to large numbers of samples. This protocol provides instructions to perform a high-throughput small molecule screen using flow cytometry analysis of THP-1 cells, a human monocytic leukemia cell line. We describe a methodology for identifying compounds that regulate PD-L1 surface expression in IFN-γ-stimulated cells, which has been successfully used to screen a collection of ∼200,000 compounds. For complete details on the use and execution of this protocol, please refer to Zavareh et al. (2020).