Fig. 3.

Effect of S. Typhimurium infection on ex vivo cytokine production by splenocytes of streptomycin-pretreated young and old mice. IFN-γ (a, b, c) and TNF-α (d, e, f) production by splenocytes from young and old mice, uninfected or infected with 1×10⁶ c.f.u. S. Typhimurium at day 4 p.i. is shown. Splenocytes were stimulated with medium, HKS, ConA or LPS for 48 h. Supernatants were collected and cytokines were measured by ELISA. (a) Non-stimulated IFN-γ; (b) HKS-stimulated IFN-γ; (c) ConA-stimulated IFN-γ; (d) non-stimulated TNF-α; (e) HKS-stimulated TNF-α; (f) LPS-stimulated TNF-α. Solid bars, young mice; blank bars, old mice; * indicates significant age-related difference in uninfected or infected mice at P<0.05 using Student's t test; # and ## indicate significant differences between uninfected and infected mice in their respective age groups at P<0.05 and <0.01, respectively, using Student's t test. Data are means±sem (n=14−18 per group) from two independent experiments.