TABLE 1.

Enzyme treatment enhances macrophage phagocytosis and neutrophil killing of encapsulated B. anthracis Ames

TreatmentaMacrophage phagocytosis (mean no. of bacilli ± SEM) (phagocytic index)Neutrophil killing (% viable)
PBS1.3 ± 0.272.0c
CapD43.0 ± 4.7b0.5d
PghP1.2 ± 0.352.5e
CapD + cytochalasin DNDg67.9f
Unencapsulated bacilli40.9 ± 2.7b0.15d
  • a Encapsulated B. anthracis Ames bacilli were treated with PBS alone, CapD, or PghP before being assayed for macrophage phagocytosis and neutrophil killing as described in Materials and Methods. A control with unencapsulated bacilli grown in the absence of sodium bicarbonate and CO2 was included. Cytochalasin D was added to neutrophils prior to the addition of CapD-treated bacilli. Results of macrophage phagocytosis experiments are expressed as the mean number of bacilli that adhered to each macrophage ± standard error of the mean. Results of neutrophil killing are expressed as the viability (percentage) of bacilli derived from measuring the CFU of duplicate samples at 2 h compared to that at time zero. Neutrophil killing data are from one experiment that is representative of seven experiments with CapD and two with PghP.

  • b P < 0.0001 compared with the PBS control (Tukey's post hoc test).

  • c P = 0.0025 compared with time zero (paired t test).

  • d P < 0.0001 compared with time zero (paired t test) and with PghP and PBS control at 2 h (Tukey's post hoc test).

  • e P < 0.0001 compared with time zero (paired t test) and with PBS control at 2 h (Tukey's post hoc test).

  • f P < 0.0001 compared with CapD-only treatment at 2 h (Tukey's post hoc test).

  • g ND, not determined.