Comparative Pyrogenic Reactivity of Rabbit and Man to Bacterial Endotoxin

Summary Comparative reactivity of mature albino rabbits (1.8–2.2 kg) and of healthy man to the pyrogenic activity of purified S. typhosa, E. coli, and Pseudomonas endotoxins is presented. On a per kilogram basis, rabbit and man are approximately equally reactive to threshold pyrogenic quantities of endotoxin. When larger doses of endotoxin are employed, the dose-response relationships become considerably steeper for man. On a total dose basis, rabbits require smaller quantities of endotoxin to elicit threshold febrile responses, but as total toxin dose is increased, febrile responses of man rapidly exceed those of the rabbit. Subjective toxic responses of man parallel the pyrogenic responses. These data provide a more definitive base line for interpreting studies with bacterial endotoxin that involve extrapolation of rabbit febrile responses to man.