Fig. 1

a Diff-Quick stain of A. phagocytophilum Webster strain in Hoxb8 neutrophils. Bacteria were grown 3 days in Hoxb8 neutrophils, cytocentrifuged onto a glass slide and stained by Diff-Quick (magnification ×1000; scale-bar: 2 μm). Arrows: morulae of A. phagocytophilum inside Hoxb8 neutrophils. b Increase of A. phagocytophilum 16S rRNA relative to murine HPRT mRNA at different time points after infection of Hoxb8 neutrophils. Results were normalised to the respective 0 h value of each sample using the ΔΔC_t-method. The inoculum was prepared from infected Hoxb8 neutrophils or infected HL60 cells. Half of the set of samples was washed 2× in PBS at 4 h p.i. and subsequently supplied with fresh medium. Mean and SD from 4 independent experiments are shown. Differences between experimental groups were analysed using the two-tailed Mann-Whitney test. The following groups were compared: Hoxb8 neutrophils vs HL60 cells (non-significant), Hoxb8 neutrophils + wash vs HL60 cells + wash (non-significant), Hoxb8 neutrophils vs Hoxb8 neutrophils + wash (significant only at 4 h p.i., P < 0.05) and HL60 cells vs HL60 cells + wash (significant only at 4 h p.i., P < 0.05). c Chemokine and cytokine production in unstimulated (medium) Hoxb8 neutrophils, in Hoxb8 neutrophils stimulated with uninfected lysed Hoxb8 neutrophils (uninfected), in Hoxb8 neutrophils stimulated with A. phagocytophilum-infected lysed Hoxb8 neutrophils (infected) or in Hoxb8 neutrophils stimulated with 10 ng/l LPS at different time points. MIP-1α, RANTES, TNF and IL-6 were measured in the supernatants using CBA assay. Mean and SD from 5 independent experiments are shown. Differences between experimental groups were analysed using the two-tailed Mann-Whitney test. Hox8 neutrophils treated with lysed uninfected and lysed infected Hoxb8 neutrophils or LPS were compared to those treated with medium only. *P < 0.05, **P < 0.01