Modulation of PD-L1 expression on B cells and dendritic cells. C57BL/6 mice received 3 Gy TBI on day −1 followed by 20 to 25 × 10⁶ B10.A BM cells with or without anti-CD154 (MR1) on day 0 (A); or anti-CD154 with or without CD4 depletion (B). Four days later, dendritic cells (CD11c⁺) and B cells (CD19⁺) were extracted from the spleen as described in “Activation markers on splenocytes” and then stained and analyzed by FCM. Dotted line represents a normal control mouse. Statistical analyses were performed with a Mann-Whitney U test. * indicates P < .05; **P < .005; and NS, not significant. One experiment is shown for panel A and one experiment is shown for panel B. Each symbol represents an individual animal.