Properties of reference Escherichia coli endotoxin and its phthalylated derivative in humans.

The properties of a reference bacterial endotoxin prepared from Escherichia coli and its phthalylated derivative were studied in normal human volunteers infected intravenously with the compounds. The minimal pyrogenic dose of the reference endotoxin is about 0.1-0.5 ng/kg. The increase in white blood cell count, absolute granulocyte count, absolute immature granulocyte count, and concentrations of serum amyloid A, cortisol, and growth hormone was directly related to the concentration of reference endotoxin administered. Phthalylated reference endotoxin up to 1,000 ng/kg (at least 500 ng of the patent compound/kg) was administered to normal human volunteers without significant changes in temperature, white blood cell count, absolute granulocyte count, and concentrations of serum amyloid A, cortisol, and growth hormone. Thus, this study defines biologic properties of the new reference bacterial endotoxin in humans and demonstrates effective detoxification by phthalylation of the present compound.