Concentrations of the cytokines IFN-γ (A), TNF-α (B), MCP-1 (C) and IL-6 (D) in lung homogenates and C. trachomatis-specific IgG titer in serum (E). A dosage of 20 mg kg⁻¹ body weight of tetracycline was applied i.p.. The cytokines were determined by the Mouse Inflammation Cytometric Bead Array. Levels of IL-10 and IL-12 p70 were below the LOD (data not shown). Means ± standard deviations are depicted. Abbreviations: B_E: Buffer (early treatment); B_L: Buffer (late treatment); T_E: Tetracycline (early treatment): T_L: Tetracycline (late treatment); groups were analyzed at different time points: 4, 6, 8 or 20 days p.i. Asterisks and hashtags indicate statistical significances: (A–D) *P = 0.05; **P = 0.01; ***P = 0.001; n.s. = not significant; ^##P = 0.01 (difference Mock/Buffer (late) versus CtrD/Buffer (late). (E) In order to show an effect due to chlamydial infection, the Mock/Buffer (late) group was compared with the CtrD/Buffer (early) group from day 20 and not, as in other analyses, with the CtrD/Buffer (late) group. The latter group was already sacrificed on day 6 p.i. and at this time point, almost no IgG response can be expected, yet.