FIG. 7.

Calculation of phagosomal pH by quantitative immunogold staining. Human MDM were infected with the live or killed F. tularensis RCI as described for Fig. 6, and DAMP immunogold particles were enumerated in the bacterial compartments and in a reference compartment (the nucleus). The pH was calculated as described in Materials and Methods. Values shown are the means ± standard errors of at least 20 bacterial compartments from each of at least two electron microscopy grids. The experiment was performed twice, with similar results.