Fig. 5.

Human TLR2 is not mandatory for NK cell activation induced by Pf-RBC, but IL-18 is required. (A) HEK293 reporter cells transfected with indicated human (h) or mouse (m) TLR were stimulated with a specific agonist for each TLR (open bars) or 3D7-RBC (filled bars) for 18-24 h. Results are represented as optical density (OD) after subtraction of the background signal obtained with RBC or medium alone. (B) The production of IFN-γ by NK cells within human PBMC in response to 3D7-RBC versus RBC was assessed in the presence of anti-TLR2 blocking mAb, compared with the isotype control (Upper, n = 5), and in the presence of anti-IL-18 blocking mAb, compared with the isotype control (Lower, n = 2). Results (means ± SD) are presented as a percentage of control calculated as in Fig. 2. (C) IL-18 production was assayed in the supernatant of purified human macrophages after 24 h of culture with Pam3CSK4, 3D7-RBC, or RBC, in the presence of medium alone.