CTLA4 and B-cell chronic lymphocytic leukemia: In our multivariable regression model, there was no association between B2M levels and PD-1 on B cells (β = 0.008, SE = 0.011, p = 0.524), PD-1 on activated B cells (β = 0.008, SE = 0.011, p = 0.525), PD-1 on memory B cells (β = 0.0008, SE = 0.004, p = 0.905), CTLA-4 on B cells (β = 0.004, SE = 0.002, p = 0.426), CTLA-4 on activated B cells (β = 0.004, SE = 0.002, p = 0.419), or CTLA-4 on memory B cells (β = 0.004, SE = 0.002, p = 0.419) in patients with CLL (Supplementary Table S1).