An Endogenous Mediator of Depression of Amino Acids and Trace Metals in Serum during Typhoid Fever

Abstract

Concentrations of most amino acids and of zinc in serum were depressed during periods of incubation and illness in 11 volunteers who developed symptoms after an oral dose of 10⁵ virulent Salmonella typhosa. When a 1.0-ml sample of sterile serum from volunteers who were ill with typhoid fever was injected into normal rats, it stimulated a prompt and significant depression of the concentration of zinc in the rats' sera and a flux of amino acids into their livers. These observations support the hypothesis that an endogenous factor (similar to endogenous pyrogen released by polymorphonuclear leukocytes) was present in the blood during typhoid fever and served as a mediator for the observed depression in zinc and amino acids in serum. The magnitude and pattern of infection-related depression in individual amino acids in serum may be, in part, a function of the amount of endogenous mediator released and of the rates of utilization of amino acids by tissues.