The effect of bacterial endotoxin on the newborn guinea pig.

Newborn guinea pigs (less than 24 hours old) are highly susceptible to the lethal effect of endotoxin and susceptibility decreases with age. The vulnerability to endotoxin has not been attributed to hypofunction of either the adrenal gland or the reticuloendothelial system of the newborn, since prior injection of corticosteroids provides only partial protection to endotoxin and newborn guinea pigs can efficiently remove colloidal substances from the circulation. In contrast to adults, newborns do not develop a delayed inflammatory reaction following intradermal injection of endotoxin, and after intravenous challenge frequently fail to display neutropenia and sustained fever.