Modification of Lethality of Endotoxin in Mice by Zymosan

Summary

Pre-treatment of mice with different preparations of zymosan modified the lethal effect of a subsequent endotoxin challenge, ranging from increased resistance to increased susceptibility, despite equivalent RES stimulation. Source and degree of heating in preparation for injection were determinants. Greater relative sensitivity to i.v. than to i.p. challenge was found regardless of the zymosan used. Protection was not attributable to endotoxin contamination or to stimulation of serum antibody titer to the challenge. Zymosan produced a monophasic fever in the rabbit, differing from the biphasic endotoxin fever, and did not elicit an acute leucopenia.