Figure 3.

The percentage of monocytes binding protective antigen (PA) (a) and the median fluorescent intensity (MFI) of levels of PA in naturally infected convalescent (n = 4), vaccinated (n = 10) and unexposed (UK) individuals (n = 7) was determined by flow cytometery. Significantly lower levels of PA binding in the convalescent samples compared to both the unexposed controls and the anthrax vaccine precipitated (AVP)-vaccinated individuals (P = 0·03 and 0·007, respectively), while PA MFI was significantly lower compared to the AVP-vaccinated subjects (P = 0·008) but not unexposed controls (P = 0·09).