CD27-trunc expression on lymphoma cells increases NK cell numbers and function. (A) Volume of Q2A-CD27-trunc and Q2A-empty lymphomas after 12 days SC injection into BL/6 mice. (B) Representative FACS plot showing frequency of NK cells in lymphoma-infiltrating leukocytes. (C) Numbers of lymphoma-infiltrating NK cells. (D) Frequency of Annexin-V⁺ NK cells. (E) Frequency of KLRG1⁺ NK cells. (F-G) Cell suspensions from tumors at day 12 were restimulated with PMA/ionomycin or anti-Ly49D–activating mAb, in the presence of anti-CD70 blocking antibody (FR70) or control IgG, and IFN-γ and CD107α expression was analyzed on CD19⁻ CD3⁻ NK1.1⁺ NK cells by FACS. (F) Numbers of IFN-γ⁺ NK cells. (G) Numbers of CD107α⁺ NK cells. (H) Histogram showing the expression of IFN-γ in lymphoma-infiltrating NK cells after PMA/ionomycin restimulation, for 3 tumor samples in each condition. (I) Δ MFI, [MFI-stimulated – MFI-unstimulated], of IFN-γ in Q2A-empty and Q2A-CD27-trunc lymphoma-infiltrating NK cells. Data are shown as mean ± SEM of 3 animals in each group (A-I) and are representative of 3 independent experiments. Statistics: Student t test (A,C-G,I).