FIG. 2.

Infection with A. phagocytophilum leads to decreased STAT1 phosphorylation and CD119 expression in neutrophil granulocytes. PMN were infected with A. phagocytophilum as described in Materials and Methods. (A) Western blot analysis of phosphorylated STAT1. A. phagocytophilum-infected and noninfected PMN were incubated for 15 min at 37°C in the absence or presence of 200 U of IFN-γ/ml. pSTAT1 was detected using an antibody specific for pSTAT1. To assure equal sample loading, membranes were stripped and reprobed with anti-β-actin MAb. The results shown are from one of three experiments that yielded similar results. (B) Flow cytometry analysis of cell surface expression of CD119. Infected and noninfected PMN were cultured for 5 h and stained with PE-conjugated anti-CD119 MAb. Filled histograms indicate the population stained with isotype control antibody for infected (dark gray) and uninfected (light gray) PMN. The fluorescence intensity of the cells was analyzed by flow cytometry. The histograms are from one representative experiment. In brackets, mean fluorescence intensities ± the SEM of three experiments are given. *, Significant (P < 0.05) difference between CD119 expression of infected and uninfected PMN.