IFN-γ stimulates CTLA4 mRNA production. (A) CLL cells were treated with 1 μM ibrutinib or acalabrutinib for 1 hour before washing and stimulation with 100 IU/mL IFN-γ for 48 hours. Total CTLA4 mRNA was measured by qPCR (n = 10 unstim, 10 IFN-γ, 9 IFN-γ+ibru, 7 IFN-γ+acal). (B) CLL cells were stimulated with 100 IU/mL IFN-γ for 48 hours and then CTLA4 expression was quantified by flow cytometry. The left 2 columns represent paired unstimulated vs IFN-γ–stimulated samples (n = 13), and the right column represents unrelated coculture-stimulated CLL cells (n = 12). Graphs show mean ± standard deviation. *P < .05 by mixed effect modeling (A) or paired t test (B). ns, not significant.