Ibrutinib inhibits cellular activation. (A-B) The percentage of CLL cells expressing the cell surface marker (A) CD69 and (B) CD86 on CLL cells from peripheral blood (PB, n = 20) was compared between pretreatment (Pre) and various treatment time points. Comparisons by paired Student t test: *P < .05, **P < .01, and ***P < .001. (C-D) The percentage of CLL cells expressing the cell surface marker (C) CD69 and (D) CD86 on CLL cells from PB (n = 30) was compared between pretreatment (Pre) and day 28. Comparisons are by paired Student t test. (E-F) Mononuclear cells from lymph node biopsies (LN, n = 8) or bone marrow (BM) aspirates (n = 10) were stained with the indicated antibody. Results shown are for the CLL population (CD5⁺/CD19⁺). The mean (± SEM) percent of (E) CD69 and (F) CD86 expressing CLL cells pretreatment (Pre) and on ibrutinib is shown. Comparisons are by paired Student t test.