Cytokine treatment increases soluble PD-L1 in the media of the WM cell lines. BCWM.1 and MWCL-1 cells were treated with 100 ng/mL IL-21, IFNγ, CCL5, G-CSF or 50 ng/mL IL-6 for 3 days. Media were collected and the level of soluble PD-L1 was determined using PD-L1 ELISA. (A) Bar graphs show the PD-L1 concentration (picograms per milliliter) in the media of the cells treated with cytokines. Data presented as mean ± SEM of 3 individual experiments and significant differences are displayed on each graph. (B) Bar graph shows IL-21– or IL-6–induced PD-L1 secretion in BCWM.1 cells in the presence or absence of 1 μM CP 690550 (left) and 0.5 μM STATTIC (right).