Figure 5: Effect of titanium dioxide nanoparticles, titanium dioxide nanotubes, and titanium dioxide fine particles on cytokine production in 48h MLR culture supernatants. C57BL/6 mice splenocytes treated with titanium dioxide nanoparticles/titanium dioxide nanotubes/titanium dioxide fine particles for 24h, fixed with mitomycin C and co-culture with BALB/c mice splenocytes for 72h. Supernatant was collected from 48h MLR and cytokine levels were measured by ELISA. Th1 cytokines interleukin-2 (a) and interferon γ (c) levels suppressed, whereas interleukin-4 (b) levels slightly elevated in the presence of titanium dioxide nanomaterials-treated stimulators. Data are presented as mean ± standard deviation of three independent experiments. Statistical significance was defined as *P < 0.05, **P < 0.01