Figure 2. Conditioned media from melanoma-associated fibroblasts decrease the susceptibility of tumor cells to NK-mediated killing.

(A–C) The lysis of the T1 melanoma cell line, untreated (Ctrl) or pre-treated during 48 hrs with the conditioned media (CM) of CAFs (CAF1-4) (A) or normal skin fibroblasts (NF1-3) (B) by the NK92 clone was evaluated by ⁵¹Cr release assays at different effector:target (E:T) ratios. Data are the mean ± s.d. from five independent experiments. Experiments in (A–B) were performed at the same time but separated in two different panels. (C) represents the mean ± s.d. of all the NK92-mediated lysis experiments from (A–B) using the CAFs or NFs pre-treatments of the T1 tumor cell line. (D–E) The lysis of the T1 melanoma cell line, untreated (Ctrl) or pre-treated during 48 hrs with the conditioned media (CM) of CAFs (CAF1, 3 or 4) or normal skin fibroblasts (NF2-3) by the NK cells isolated from two healthy donors (NKd1 and NKd2) was evaluated by ⁵¹Cr release assays at different effector:target (E:T) ratios (D–E). Data are the mean ± s.d. from three independent experiments. (F) represents the mean ± s.d. of all the NKd-mediated lysis experiments from (D–E) using the CAFs or NFs pre-treatments of the T1 tumor cell line. P values (C–D) were determined by unpaired two-tailed student's t-test comparing the control and CAFs CM pre-treatments. (*p < 0.05; **p < 0.001)