*4.6. RNA Extraction, Reverse Transcriptase and Real-Time Quantitative PCR*

Total RNA was extracted using TRIzol reagent (Life Technologies) from 10<sup>6</sup> LCLs and DLBCLs cells treated or not. Total RNA (1 μg) was reverse transcribed using the high capacity cDNA Reverse Transcription Kit (Applied Biosystems) according to the manufacturer's instructions, with 20μL of final reaction volume. Quantitative mRNA relative expression of PD-L1 was performed in triplicate, with 50 ng cDNA, using the Taqman Assay Gene Expression system of PD-L1 (Hs01125296\_m1) or GAPDH–internal control–(Hs02758991\_g1) (both from ThermoFisher Scientific) with SensiFast Probe HiRox Mix (Bioline), on a Quant Studio3 cycler. Each quantitative PCR was performed in triplicate. The expression level of each gene was normalized to the GAPDH expression level. The calculated relative mRNA expression level was equal to 2-ΔΔCt with untreated cells (control) as reference.
