Role of Macrophage Oxidative Burst in the Action of Anthrax Lethal Toxin

Table 1 Effects of antioxidants on edema toxin and lethal toxin actions in RAW264.7 M ϕ cultures

		Percent of Initial Toxin Activity
Antioxidant	Concentration	EdTx^a	LeTx^b
None	—	100%	100%
DTT	10 mM	91	3
BME	10 mM	94	6
EtOH	10%(v/v)	99	12
DMSO	10%(v/v)	108	7
ascorbate	100 mM	95	21
α-tocopherol	100 mM	90	18
mepacrine	100 mM	88	10
NAC^c	50 mM	99	5
met^c	100 mM	103	9

^aEdTx-induced increase of cellular cAMP was determined by radioimmunoassay, using a cAMP scintillation proximity assay. 100% activity is defined as the amount of cAMP in cells (950 fmol/µg protein) 45 min after addition of toxin (0.1 µg PA + 0.1 µg EF/ml), after normalization for cAMP present in untreated cells.
^bLeTx-induced cytotoxicity was measured by release of ⁵¹Cr from prelabeled cells (see Fig. 1 legend).
^cNAC and met were preincubated with cells for 16 hr before toxin challenge (see Fig. 3).

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