Fig 5.

Depletion of heterophils decreases host resistance to toxin-negative B. anthracis mutant. The bacterial burdens in the LALN and spleens 72 h after a pulmonary inoculation with PA− mutant spores in untreated rabbits and rabbits that had received a 0.75-mg/kg dose of vinblastine (Vin) i.v. 1 day prior to challenge were determined. An average 93% decrease (range, 92 to 96%) in heterophil levels was observed at the time of harvest in vinblastine-treated rabbits. The experiment was performed twice (average of 2.5 × 10⁶ spores/Rb; n = 3 to 4 Rb/group/time point/experiment). One vinblastine-treated rabbit died prior to 72 h harvest. The LALN CFU levels were significantly different between untreated and vinblastine-treated rabbits (P < 0.005).