Fig. 2.

Circulating LT attenuates PMNs killing of vegetative B. anthracis. (A–C) C57Bl/6 mice were injected with toxin components (LF, PA) and PMNs were isolated at 24 h post injection. PMNs were then inoculated with TKO at an moi of 1:1 and incubated at 37°C. At indicated time points samples were put on ice and mixed with 0.1% Saponin for 10 min and vigorously mixed by pipetting. Samples were then serially diluted and plated for enumeration on LB agar.

A. Mice were injected i.p. with the indicated doses of LT, PMNs were isolated at 24 h post injection and cfu were determined at indicated time points. Significant differences in cfu over time were found between non-intoxicated and + 6.25 μg LT (0.5 h **P < 0.01, 1 h ***P < 0.001, 1.5 h **P < 0.01) and 6.25 μg LT and 1.56 μg LT (1 h *P < 0.05 and 1.5 h **P < 0.05).

B. Mice were injected i.p. with LF or PA, PMNs were isolated 24 h post injection and cfu were determined at indicated time points.

C. Mice were injected i.p. with 6.25 μg LT and PMNs were isolated from the bone marrow at 3, 6, 24 and 48 h post injection and their ability to kill TKO ex vivo was determined. Significant differences were seen between 6 h LT-treated PMNs and non-intoxicated PMNs at 1.5 h (*P < 0.05) and 24 h LT-treated PMNs and non-intoxicated PMNs at (0.5 h **P < 0.01, 1 h ***P < 0.001, 1.5 h **P < 0.01). n = 3 mice per condition.