Bio glotm assay reagent

The activity of the inhibitors of hPD-1/hPD-L1 immune checkpoint was examined using the hPD-1/hPD-L1 Blockade Bioassay (Promega), according to the manufacturer’s instructions. hPD-L1 aAPCs were seeded on 96-well (white) plates at the density 10 000 cells/well 17h prior to the experiment. The 2.5-fold dilutions of the small molecules or peptide-57 were first prepared in DMSO. On the day of the assay the compounds were diluted 1000-fold in the assay buffer (99% RPMI 1640, 1% FBS) to maintain the constant concentration of DMSO (0.1% of total volume). The 2.5-fold dilutions of nivolumab, a positive control anti-hPD-1 monoclonal antibody (Opdivo, Bristol-Myers Squibb, New York, NY, USA), were prepared in the assay buffer on the day of the assay. The culture medium was discarded from the wells and serial dilutions of either the small-molecule or antibody was added. Afterwards, Jurkat hPD-1 cells were seeded at the density of 20,000 cells per well in the assay’s plates. After 6h of the incubation in standard culture conditions, assay plates were equilibrated at ambient temperature for 10min, followed by a 20min incubation with the Bio-GloTM Assay reagent (Promega). The luminescence was detected using the Infinite M200 reader. Half maximal effective concentrations (EC₅₀ values) were calculated from the Hill’s curve fitting to the experimental data.