Level of soluble PD-L1 and PD-L2 concentration in the BM plasma as well as peripheral blood serum of the patients with WM. Normal and WM BM samples were processed to separate cells from BM plasma containing soluble factors. Peripheral serum samples were collected from WM patients and normal donors. The concentration of PD-L1 and PD-L2 on these samples was determined using ELISA. (A) Dot plots compare mean ± SEM of PD-L1 and PD-L2 between WM and normal samples. Normal BM plasma, n = 20; WM plasma, n = 28; normal serum, n = 20; WM serum, n = 52. (B) Dot plots compare the PD-L1 and PD-L2 levels between normal, smoldering, and symptomatic WM patients, as well as MyD88⁻ vs MyD88⁺ WM patients. Significant differences and the P values are shown on each plot.