Influence of body weight on response of Fischer 344 rats to anthrax lethal toxin.

Groups of Fischer 344 rats were injected intravenously with Bacillus anthracis culture supernatant containing crude anthrax toxin. Times to death of rats given identical toxin preparations varied directly with the weights of the rats (P = 0.0001). In contrast to previous reports, the data indicate that rat weight must be taken into account during in vivo assays of anthrax lethal toxin activity.